The Tropical Fruit Forum

Citrus => Cold Hardy Citrus => Topic started by: kumin on January 25, 2019, 08:04:22 AM

Title: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 08:04:22 AM
I'm trialing a population of F2 Citrange seedlings this winter in zone 6b in SE PA. There is considerable variability in the resistance to low temperatures, with some dying in November and others still viable at this point. The population is a mixture of nucellar  F1 and zygotic F2 seedlings. The F1 are freezing out at present, but a number of the F2 are surpassing the F1 in hardiness and a few appear to be surviving the winter. My hope is that several will approach the hardiness of P. trifoliata.

Any survivors would then be evaluated for palatability. My focus is centered on hardiness, with palatability being secondary.

I've grown poncirus since 1980 and lost everything above the snowdrifts in Jan of 1994. This was after 2 consecutive nights at -24 F. The trees resprouted below the snow height and haven't been injured since.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on January 25, 2019, 01:10:14 PM

I've grown poncirus since 1980 and lost everything above the snowdrifts in Jan of 1994. This was after 2 consecutive nights at -24 F. The trees resprouted below the snow height and haven't been injured since.

kumin, Thanks for this information.  Where are you growing poncirus?  Full sun, partial shade, protected from the wind?  Have you noticed any difference between poncirus plants? 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 01:42:38 PM
hardyvermont, I have Poncirus plantings at three locations on the same property. All are in clay soil, one location  is well drained , the remaining two are poorly drained. The trees growing in full sun have the the most vigor. Last winter I removed a M. Grandiflora tree that was shading the largest Poncirus tree and upon release the Poncirus  tree responded positively. Most of my trees are fairly close to buildings which could block or concentrate the wind. I haven't recently germinated  Poncirus seedlings on large scale. When I did in the past, I saw the occasional seedling I suspected of being tetraploid. Due to generally having rather high % of nucellar (clonal copies) seedlings, one usually sees a lot of uniformity.

The citranges by contrast have no wind protection other than the density at which they're planted. They are planted at about 20 seedlings per sq. ft.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 01:58:21 PM
hardyvermont, I lost a planting of first year Poncirus a few decades ago by planting them into loosely cultivated soil and not allowing the soil to solidify during the growing season. During the winter 500-600 succumbed to late winter frost heave. In early April I could very easily pull the dead trees out by hand. They were approximately a foot tall at that time. There were no survivors. Mulching the soil might have saved them all.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 25, 2019, 03:04:53 PM
What  is your source of citrange seeds?
I'm glad to know someone else in the USA is growing F2 citrus x trifoliate hybrids. But mine are still at the tiny seedling stage, certainly not ready to face zone 6 winter.  In fact,  I assume I'll need at least one backcross to trifoliate, maybe two.  I would love it if you proved me wrong.
Keep us up to date on your results
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 07:53:36 PM
Walt, being of similar age as you, I am using brute force (large populations) in an attempt to increase the odds of obtaining very hardy F2 segentranges in a short time span. After planting a number of putative " cold hardy " cultivars that failed, I am seeking plants with nearly the full hardiness of Poncirus.  I began with an initial population of 20,000+ seedlings. The seedlings are 85% nucellar and 15% zygotic, so the effective population under trial  is 3,000 plants.

The seeds were germinated in April of 2018 and planted outdoors in June, 2018. These plants are not protected against the cold in any way. Survivors, if any, will be protected going forward, knowing they have the necessary genetics. At this point the population will be very small and easier to protect.

Googling  "citrus tree seed California" will give you 2 hits that sell seed by liter or quart. If you need details on how to germinate large quantities of Citrus seed I can't make a recommendation, but I can tell you how I did mine.
(https://i.postimg.cc/LqvM71Vm/IMG-20180508-133913-1.jpg) (https://postimg.cc/LqvM71Vm)

(https://i.postimg.cc/hhXqyhQq/IMG-20180602-064120-1.jpg) (https://postimg.cc/hhXqyhQq)

(https://i.postimg.cc/sQ8bd9GC/IMG-20181224-112926.jpg) (https://postimg.cc/sQ8bd9GC)
Title: Re: F2 citrange winter hardiness trial
Post by: Florian on January 26, 2019, 04:45:45 AM
Check out the Hamlin x FD: http://tropicalfruitforum.com/index.php?topic=28270.msg321750#msg321750. (http://tropicalfruitforum.com/index.php?topic=28270.msg321750#msg321750.)
It appears to be rather coldhardy.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 26, 2019, 02:33:55 PM
Kumin
3,000 is a number I can respect.  I stated in long term cold hardy thread why I think F2 citranges will be less cold hardy than than F1.  But 3,000 trys?  If I'm wrong about even one of them, you win.  This is a real effort.
I think your chances would be better with older trees.  But you are doing a big job, so do it your way and I hope you succeed.
Thanks for the information about seed source.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 26, 2019, 02:48:24 PM
HamlinxFD is certainly not hardy in zone 6.

I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.

For the germination, from my experience, the best method is perlite/buggy approach used for palm seeds.
Seeds are germinated in zip locked plastic bag in moist, but not wet perlite at 25C. After germination seedlings can be transplanted in common pots to grow under artificial light and transplanted in  spring in the open ground.
I am germinating each season around thousand of seeds  by this method (my record is 3000), selection to discard nucellar seedlings  and plants with poncirus aftertaste in leaves can be done very early, before open ground planting.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on January 26, 2019, 02:56:35 PM
I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.
I just looked at my germinating US852 seeds. Four of them had begun sprouting, and of those 2 of them were polyembryonic and 2 only had single sprouts.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 02:59:03 PM
3,000 is a little less impressive than it sounds, approximately half are genetically dwarf which is not unusual for F2 zygotic citranges. Many of them are too lacking in vigor to hold much promise. Long story short- I did a status survey today and believe 100 to 150 plants are relatively unscathed, but February can be brutal to plants. Some winter cold damage is accumulative, as any individual cold event can be. The best looking plants phenotypically favor Poncirus rather strongly. However, they are not identical to one another in appearance. Hopefully they will carry some Citrus genes.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 04:32:51 PM
The germination technique I used, was placing the seeds in mesh bags, then using a repurposed dishwasher with thermostatic control of water temperature, aerated/soaked them for 24 hours at 86 degrees F. I then removed them and scarified the seed coat for 30 minutes, followed by neutralizing the solution and rinsing them thoroughly. They were then returned to another 24 hrs of soaking, followed by planting immediately into a germination bed, again at 86 degrees F. They were planted 1 centimeter deep. Areas cooler than 86 degrees had a bit of seed decay. Seeds planted too shallow lifted out of the soil. Seeds planted too deep had delayed emergence. Emergence began at 7 days and continued a little over a week.

 The seed soaking procedure was used, as the seed was stored, dry seed. This would be unnecessary with fresh seed. Soaking the seed helps to synchronize the germination and subsequent emergence of seedlings.

The water used in the soak was slightly chlorinated to prevent decay. The water was drained and replaced every 6 hours. As the seedlings grew larger and May weather became warmer the bed temperature was dropped to 75 deg. F. The seedlings were field planted on June 12, 2018. By end of September the tallest seedlings were 48" tall. The average was closer to 30" - 36 " tall.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 06:42:50 PM
Ilya 11 Thanks for your suggestion of a leaf taste test. During field planting I noticed some plants were pleasantly sweetly aromatic, but I didn't trust that there was a definitive correlation between plant sap taste and fruit taste. Relying on such a test could dramatically reduce the time, labor, space, etc. required to plant seedlings.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on January 27, 2019, 01:18:28 AM
I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.
Yes, US 852 is a hybrid between Changsha mandarin (already pretty hardy) and trifoliate, and can survive well into zone 7.

Apparently their flavor isn't too terrible. There's a video where one guy is managing to enjoy eating them.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 27, 2019, 01:35:39 AM
I've been away from my computer a few hours, but this hasn't been out of my mind.  Kumin. your results so far alreadyshow  that I was wrong that all the F2 would be less hardy than the F1.  You said ALL your F1s are dead, but some of your F2s live.  I really didn't expect that.
You made my day.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 03:26:06 AM
Photos taken yesterday of one plant lacking hardiness and one showing little damage.

(https://i.postimg.cc/HVQRjd07/IMG-20190126-123936.jpg) (https://postimg.cc/HVQRjd07)

(https://i.postimg.cc/kRSZQdkz/IMG-20190126-124019.jpg) (https://postimg.cc/kRSZQdkz)


Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 27, 2019, 03:54:43 AM
I then removed them and stratified the seed coat for 30 minutes, followed by neutralizing the solution and rinsing them thoroughly.
Kumin,
I do not understand what do you mean by stratification? Certainly not cold treatment, may be washing soda incubation?
Your brute force approach is very impressive, hopefully it will produce some hybrids as resistant as poncirus. Still, most of the freeze damage occurs in spring when small stem cracks begin to be infected.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 04:56:13 AM
Ilya11, Yes, it was a strictly controlled alkali treatment followed by water flushing, again followed by weak acid rinse. then flushed repeatedly. At this point the final 24 hour soak was begun. I've just noticed I referred to the process as "stratification" my intent was to say "scarification".
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 27, 2019, 05:19:14 AM
kumin, you are doing impressive work!
Just a notification there is a Citrandarin F2 (but it could be F3 too) in Germany fully hardy and very similiar to Poncirus but not zone 6 more like zone 7.
It is a HRS 899 (or offspring of it) but unknown which one. There are (or were) HRS 899 a to k . All HRS 899 are offspring of US852 or another hybrid with Changsha x Poncirus parentage.
(https://farm8.staticflickr.com/7819/39926758763_9fe2644d06_z.jpg) (https://flic.kr/p/23Qc5mt)

on the left HRS 899 to the right Poncirus

 (https://flic.kr/p/23Qc5mt)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 05:38:31 AM
Thanks, Mikkel the reversal of the hybrid retaining the fruit while dropping the leaves is interesting. One aspect of Poncirus fruit is the rapid dropping of the fruit followed by short storage life. I have no experience with the variability of Poncirus hybrids fruit storage life.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 27, 2019, 02:42:50 PM
@Mikkel I can confirm your observation. Fruits of HRS89 (Poncirus x Changsa F2) stay much longer on the tree than the fruits of Poncirus trifoliata. See also my other post with photo here: http://tropicalfruitforum.com/index.php?topic=30863.0 (http://tropicalfruitforum.com/index.php?topic=30863.0)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 27, 2019, 06:02:12 PM
@usirius
I have the feeling this picture might be yours? Is it?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 03:16:15 AM
Yes mikkel, the picture above including the text has been done by myself some years ago ;-)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 28, 2019, 05:43:43 AM
I knew it :) We had some contact then.
Shall I put your name under the picture?
Is this 899 above the same as the pear shaped one you posted in the other thread?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 05:59:04 AM
Concerning the picture all is okay! On the first view I think it is the same HRA 899 selection. If helpful can check this in my garden to a later time. -  But which selection is it? The foliage is mostly trifoliate. Thank you also for the hint to find the description of Bernhard Voss- I catched the direct link to this descritption: https://web.archive.org/web/20130106094639fw_/http://www.agrumi-voss.de/hrs.htm (https://web.archive.org/web/20130106094639fw_/http://www.agrumi-voss.de/hrs.htm)    ->   This description is very old and it is related to the habitus of relatively young plants. It is possible that shape and size of foliage varies during aging. So a more actual description including fruits would be very interesting. Do you know if Bernhard Voss has done any newer documentation of the HRS899 selections - may be he published a book about those or has written something about them in an article in a garden journal?
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 28, 2019, 06:30:57 AM
I spoke several times with him. As far as I know he has no plants left. Some years ago he gave most of his plants away. I picked what seemed to be interesting but there were only 899 J and A among the plants.
Meeder, Eugen Schleipfner and CitrusBali might have some other varieties. But it seems many have lost the letter so it is often only HRS 899.

Yes I think the mature plants might have different leaves now. In his description only O and Q are fully trifoliate .
Here  (https://web.archive.org/web/20110906153931fw_/http://www.agrumi-voss.de/frosttab.htm) you can find some results from the cold tests.

How many HRS 899 do you have?
Could you check your plant again I am very interested.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 28, 2019, 08:08:51 AM
Mikkel, thanks for the winter hardiness information. It's apparent there's a great deal of variation between individual cultivars.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 02:05:28 PM
@ Mikkel: I started with about 8 selections of HRS899. Only the selections survived after the first winter. Another selection died next winter, and for many years I had only two selections left. I'm not sure, maybe three or four years ago one of the two remaining selections died. After all these years only this one has survived and this selection is as robust in my opinion as Poncirus trifoliata. It showed no damage in all winters in the past. Even an early warm-up in the spring with subsequent freezing is no problem for this selection. This is often a big problem for most "robust" citrus hybrids and selection. The only negative feature is that the fruits are inedible - smaller and a worse taste like poncirus fruits ;-)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 29, 2019, 09:46:09 AM
Kumin,
I wonder if you observed the seedlings with  tendency of autumn leaf yellowing/falling ?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 29, 2019, 11:59:46 AM
Ilya11, There is considerable variation in leaf color, some are very dark green, some are showing a bronzing response to the cold. Others show a reddish tint where the leaflets join the petioles. The F1 seedlings are uniformly dark green and shriveling as they desiccate. There are a number that have a yellowish cast, but most leaves have not dropped at this point.

One thing to keep in mind is that straight Poncirus often isn't reliably deciduous until the third year. I'm attaching a photo of self seeded 2-year old pure Poncirus that have changed color somewhat, but still haven't dropped their leaves.

(https://i.postimg.cc/XXNxW2x5/IMG-20190128-120620.jpg) (https://postimg.cc/XXNxW2x5)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 29, 2019, 12:06:52 PM
Thank you, I am quite convinced that for the robust hardiness beyond zone7, the citrus hybrid should drop its leaves in autumn. Among my F1xcitrus seedlings such plants are extremely rare.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 29, 2019, 12:40:52 PM
Ilya11, I agree with you. It's very likely that being evergreen puts too much stress and demands on the plants. There are a few plants that have dropped their leaves. I am not certain if this is from stress or preparation for winter. The trees I favor at present may not be the best in the next several months.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 01, 2019, 01:45:57 PM
The present low temperature event has struck the local area. Recent daytime highs are approximately +15 deg. F., today is expected to reach +20 F. Local lows have been +3 F,   -11.8 F, +2 F and tonight + 10 F. The - 11.8 F reading was considerably lower than the forecast. These midwinter temperatures aren't a problem for Poncirus. Concerning the F2 citranges, however, this is a severe test. I will survey the plants again once we get a prolonged thaw .  Survival is obviously not assured. A thaw is forecast to begin tomorrow. If any manage to survive they will be protected in subsequent winters.

(https://i.postimg.cc/w3v69CCs/IMG-20190131-071746.jpg) (https://postimg.cc/w3v69CCs)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 01, 2019, 06:26:06 PM
At least  all your C35 nucellar seedlings will be dead, C35 is probably the least hardy of all citranges.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on February 02, 2019, 12:24:02 AM
Citranges are not as hardy as citrandarins or citrumelos because oranges are not as hardy as mandarins or the vigorous grapefruit varieties that citrumelos were bred from. (Though I don't think the difference is huge)

However, I predict we'll see a lot more hardiness manifest in the F2 generation, at least in 25 percent of the seedlings.
That's because another cross has the chance to eleminate dominant genes that may carry cold vulnerability, or manifest recessive genes that would carry cold hardiness.
When you have an F1 cross, you're pretty much guranteed that 50 percent of the genes are going to come from poncirus and 50 percent from orange, but when you take that hybrid and cross it again, even if it's with itself, there are a lot more possibilities.
You might (though exceedingly unlikely) even be able to manifest all the good genes from the edible orange parent with all the beneficial cold hardiness genes from the poncirus parent.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 02, 2019, 05:18:54 AM
Poncirus contains several gene regions responsible for its freeze resistance and its genome is highly heterozygous. That is why  F1 hybrids with citrus are showing a large variation for winter hardiness.
Three hundreds of its F1 hybrids with very frost sensitive pummelo show a wide distribution of freeze damage.

 article (http://journal.ashspublications.org/content/128/4/508.full.pdf)

(https://b.radikal.ru/b13/1902/bb/5a2a6f76c8cf.jpg) (https://radikal.ru)

Quite possible that C35 citrange inherited a rather unfavorable set of gene alleles from its poncirus parent explaining its poor winter performance.
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on February 02, 2019, 02:06:25 PM
For forum members reading through this post, that are not familiar with what the variety HRS 899 is see below:

Newly bred variety, the tests havent been finalized yet. It is a cross of tangerine variety 'Changsha' and Poncirus. It grows well and fast, has only simple leaves and is significantly hardier than the citranges 'Rusk' and 'Morton'. Its flowers are small, comparable to those of tangerines. B. Voss says about 15 clones labeled HRS and a capital letter, of which the clone 'HRS-899 J' is supposedly hardy to -15C and the clone 'US 899 F' has much more vigorous growth. Its leaves mono-, di- and trifoliate and its a little bit hardier.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 03, 2019, 03:30:55 PM
Today's high temperature is 45deg. F. I've taken a few photos to see how the best plants have fared. Most look similar, but a little worse for wear and tear. The best ones look to be in similar condition to my Poncirus of similar size. These may have a chance at survival.

This is after almost a week of temperatures below freezing, the lows ranged from +3 deg. F. to -11.8 deg F., there were several days of high temperature +/-  +15 deg F. I am pleased with the results thus far, but percentages of plants looking this good are low.
Of special interest to me is plant # 3 having a mixture of unifoliate and trifoliate leaves.


(https://i.postimg.cc/yDD5Z7BM/IMG-20190203-145004-1.jpg) (https://postimg.cc/yDD5Z7BM)

(https://i.postimg.cc/yW7bTmsX/IMG-20190203-144804-3.jpg) (https://postimg.cc/yW7bTmsX)

(https://i.postimg.cc/BXXNhNyD/IMG-20190203-144536-1.jpg) (https://postimg.cc/BXXNhNyD)

(https://i.postimg.cc/V5HWbn6N/IMG-20190203-144403.jpg) (https://postimg.cc/V5HWbn6N)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on February 03, 2019, 05:47:57 PM
This is after almost a week of temperatures below freezing, the lows ranged from +3 deg. F. to -11.8 deg F.,
It's surprising that anything that's not pure poncirus could survive -10 F.
I'd view this as a success.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 03, 2019, 05:58:59 PM
At this point I'm debating protecting a few of the most promising specimens for the rest of the winter, in order to preserve their genetics. It would be a deviation from my original plan, but I already have $2,000.0 in this project and it might be prudent.

Although I can be certain that the seed parent is F1 C-35 citrange, there is no definitive proof that the pollen parent is the same. Depending on blooming time and seed grove layout, the pollen parent could be  potentially be a citrumelo, or different citrange.
Title: Re: F2 citrange winter hardiness trial
Post by: Citradia on February 03, 2019, 07:11:51 PM
The damage wont show right away. The leaves and green in the branches will slowly turn brown starting at tips and the dead brown tissue works its way down to the trunk and then to the ground. Ive had trees stay green until spring and then die. Look for cracks in trunks near the ground. If cracks form in trunks, probably gonna die. -15 degrees F and below freezing for a week, unprotected seedling poncirus hybrids, no. Miracle if some make it, and I would love to buy a specimen from you. I wish you the best in your endeavors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 04, 2019, 03:15:35 AM
At least some of them will sprout from the roots. For me, the most promising is  the last plant, for the first three the stems are already damaged.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 06, 2019, 08:04:37 AM
Here are 2 photos showing responses of:

 # 1: F2  citrange seedlings and  the variability in cold resistance after a cold week with a low of -11.8 F. at the lowest.

 # 2: Poncirus  that hadn't dropped it's leaves.  Observed on a plant not fully hardened off.

(https://i.postimg.cc/WDnJH8ZX/IMG-32.jpg) (https://postimg.cc/WDnJH8ZX)

(https://i.postimg.cc/sGgmNbqf/IMG-20190206-065345.jpg) (https://postimg.cc/sGgmNbqf)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on February 06, 2019, 08:33:31 AM
wow, if it stays like that you found your hardy F2 hybrid.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 06, 2019, 09:11:25 AM
Thanks, I am hopeful. Both photos were taken today and both plants were exposed to the same temperatures. I realized that there are still many weeks until April 1. when I consider all danger to be past.

I have noticed that the slight red color where the leaflets join is not an indication of cold adaptation, but rather an indication of tissue damage.

Poncirus indication of cold damage closely parallels that of the citranges. A few of the citranges appear to have hardier leaves than the Poncirus progenitor, this may only be because Poncirus would have dropped it's leaves at that degree of maturity on that position of the stem.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 08, 2019, 04:34:39 PM
This continues to be an educational experience. The local cold weather has been followed up by warmer temperatures and rain.
 A few observations:
1. Poncirus leaves and twigs that appeared to be wilted and dying have re-hydrated remarkably quickly.
2. The combination of direct sunlight and frozen soil is very dehydrating.
3. Subzero temperatures with no wind on a clear night allows a super-chilled  layer of air to form directly on top of the snow, which is very harmful, this layer was about 6" deep. I don't have record of the actual temperature of this layer, as the reading of -11.8 F. was about 30" above the snow.
4. The section of the stems above the bottom 6 inches showed considerable less damage than the lower 6".
5. The rather quick warming trend allowed some damage to be visible within days.
6. Some bark splitting is becoming apparent.
7. There will likely be additional observations over the next 6-7 weeks, perhaps longer.
8. Photos of Poncirus before warm up and after warmup and rain. This should be the same twig.
9. This Poncirus tree was planted in the early 90's.

(https://i.postimg.cc/Mf2M5R5y/IMG-20190206-065345.jpg) (https://postimg.cc/Mf2M5R5y)

(https://i.postimg.cc/fJnK8qR0/IMG-20190208-162702.jpg) (https://postimg.cc/fJnK8qR0)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on February 09, 2019, 11:34:17 AM
Kumin, excellent post, very detailed.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 15, 2019, 12:10:08 PM
After a new survey of the F2 citranges, I remain cautiously optimistic. The best looking plants remain quite consistent, although a portion of previous candidates look less promising. The best contenders are likely well under 1 percent of total plants.

One factor in their favor is the fact that our area has had record high moisture levels since July of 2018. The plants should have been well hydrated at any time the soil hasn't been frozen. An other unanticipated factor may be the black plastic film used for weed control. I suspect this will lessen the freeze/thaw effects to some degree.

There's an attached photo of a Southern Magnolia cv. 24 Below. This is included to gauge the impact our cold event had on other plants with hardiness similar to Poncirus. All cold damaged leaves will be shed during the May flush of new growth.

(https://i.postimg.cc/hXngK6sk/IMG-20190215-114205.jpg) (https://postimg.cc/hXngK6sk)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 22, 2019, 02:46:10 PM
Updated status of best looking F2 citranges. Some are belatedly dropping their leaves rather than shriveling on the plant. I'm edging closer to believing there will be survivors, but very few, perhaps 10 - 20 or so. March will bring it's own challenges, but the chance of getting sub-zero temperatures is decreasing.

(https://i.postimg.cc/xNz3sKQc/FEB-21-2019.jpg) (https://postimg.cc/xNz3sKQc)

(https://i.postimg.cc/8J3bBZq2/FEB-21-2019-B.jpg) (https://postimg.cc/8J3bBZq2)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 09, 2019, 05:44:12 PM
An update as winter is just starting to ease up. All photos were taken today. All plants are in ground except the first, which I potted up to allow for better protection and mobility. This plant went through all the cold  -11.8 F, etc. the rest did except for the last several nights when it had been potted.

One of the better survivors, I expect this plant to survive with stem intact. I potted the plant to allow movement to a permanent secure location. (F2 citrange)
Conestoga # 001
(https://i.postimg.cc/s1R452sM/IMG-20190309-113440-1.jpg) (https://postimg.cc/s1R452sM)

A deciduous plant I believe to be a survivor. although an F2  citrange, it resembles a vigorous Poncirus. (F2 citrange) Conestoga # 010
(https://i.postimg.cc/vxQnkcZX/IMG-20190309-064558.jpg) (https://postimg.cc/vxQnkcZX)

A cold injured Poncirus seedling,  looks worse than the very best F2 plants. (Poncirus)
(https://i.postimg.cc/30BRv17F/IMG-20190309-065014.jpg) (https://postimg.cc/30BRv17F)

20,000 - 21,000 mostly dead citrange plants. Very few of these plants are alive. (citranges)
(https://i.postimg.cc/YGDDCKL6/IMG-20190309-063621.jpg) (https://postimg.cc/YGDDCKL6)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 09, 2019, 06:06:42 PM
Great! Congrats!
Mass selection always works :)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 10, 2019, 06:16:16 PM
Good news.
Let's hope that spring will not bring  infection at the frostbites.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 14, 2019, 12:20:03 PM
I've been monitoring both the Poncirus and Segentrange as they respond to warmer temperatures. Obviously neither one is pushing buds at present. Except for vulnerable late season growth, the Poncirus have no visible changes, just waiting on warmer temperatures in a few weeks to break dormancy. The great majority of the F2s are showing various indications of cambium failure. The outer layer of bark (rind) can be green as well as leaves. As warmer temps act on these plants the rind turns either brown in the upper portions of the stems, or splits in the lower parts of the stem. the underlying cause appears to be the same, cambium failure due to cell rupture due to freezing.

I then checked the cambium on healthy Poncirus twigs and saw the cambium was green, tight , and drier. The F2s had more succulent cambium, likely more susceptible to cell rupture under freezing conditions. 

There appear to still be a very few surviving F2s, perhaps as few as 10 plants. I am monitoring these intensely, my hope is there will be signs of growth within the coming month. In a sense there may be a race between delayed tissue failure and new invigorating growth.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 14, 2019, 03:06:11 PM
If you have 10 still alive, that is 10 more than I expected.  I hope so.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 14, 2019, 03:13:49 PM
This is the most impressive I've found so far, there are potentially more, but I'll probably wait until nature takes it's course a bit further.

I can't find any bark or stem defects on this one.

Conestoga # 001

(https://i.postimg.cc/CZrFDMpM/IMG-20190314-144830.jpg)

 (https://postimg.cc/CZrFDMpM)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 16, 2019, 11:42:06 AM
Here are photos showing Poncirus bud scales followed by several F2 citrange buds showing variation from citrus-like to Poncirus-like.

Poncirus bud with scales
(https://i.postimg.cc/N9ZBJ3hc/Poncirus-bud.jpg) (https://postimg.cc/N9ZBJ3hc)

F2 buds resembling Citrus

(https://i.postimg.cc/BjnkFmyc/Segentrange-bud.jpg) (https://postimg.cc/BjnkFmyc)

F2 buds on deciduous plant resembling Poncirus buds.
Conestoga # 010

(https://i.postimg.cc/vg7Dn8gK/Poncirus-like-bud-scales-on-F2-Segentrange.jpg) (https://postimg.cc/vg7Dn8gK)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 16, 2019, 01:36:25 PM
Looks like you have something extremely hardy. I would graft it on poncirus in order not to lose due to potential bark infection.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 16, 2019, 02:04:51 PM
Ilya, I plan on keeping reserve stock for all of the hardy specimens I find. I don't want to lose any of the hardiest genetic material. If the best specimens aren't good enough for consumption they may serve as parents in breeding more advanced individuals.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 18, 2019, 06:41:12 PM
I think there is also a high potential for the hardy decorative citrus with fragrant flowers and shiny autumn fruits.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 18, 2019, 06:57:49 PM
Ilya, I've considered aesthetic use, especially if the deep orange coloration might be inherited from its blood orange grandparent. There are at least another 6 trees that appear to be hardy. There are also a number of very dwarfed plants that appear unharmed. These were likely under snow cover during the coldest periods. Perhaps a purpose could be found for these also.   
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 23, 2019, 03:13:43 PM
By now the F1 seedling's lower trunk bark has turned into mush, easily pinched and slid off the underlying wood. The few remaining hardy F2 seedlings still have intact bark. .
This F2 specimen is deciduous, showed some dehydration, but no bark destruction due to freezing.
(https://i.postimg.cc/c646CKVD/pseudoponcirus.jpg) (https://postimg.cc/c646CKVD)
 this plant has a long taproot.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 23, 2019, 07:20:30 PM
Three nucellar F1 , one resistant zygotic F2?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 23, 2019, 07:33:30 PM
Seedling # 4 could be a non-hardy F2, or an F1. At this point the fact that a few hardy F2 specimens surpass the F1 hardiness has become very certain. The majority of the F2s were no more hardy than the F1. The partial hardiness of the F1 population was very uniform as expected.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 27, 2019, 05:14:06 PM
I apologize, this is not a very clear photo. This is another deciduous F2 citrange I found today. It doesn't show any damage at the top of the snow line. If this one isn't as hardy as Poncirus, it approaches it very closely from what I can determine. Now to find how much it differs in fruiting aspects! I hope it's not an exact replica of Poncirus.
(https://i.postimg.cc/3WYNj4jz/F2-Mar-27-2019.jpg) (https://postimg.cc/3WYNj4jz)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 27, 2019, 05:34:02 PM
Now to find how much it differs in fruiting aspects! I hope it's not an exact replica of Poncirus.
(https://i.postimg.cc/3WYNj4jz/F2-Mar-27-2019.jpg) (https://postimg.cc/3WYNj4jz)
But if so offspring could be still interesting. In many years from now :)
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 28, 2019, 02:29:44 AM
Congratulations!  I admired the effort, but didn't think it would work.  Still a long way to go to get good hardy citrus, but you made a huge step.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 28, 2019, 05:25:10 AM
Walt, yes, it may in essence be a modified Poncirus. Which is a good approach for me, as I will need all of Poncirus's hardiness. This location is fairly near the limit for Poncirus, so introducing a bit of hardiness into conventional Citrus will not work. A better approach here is to tweak Poncirus to improve edibility.

As I stated initially, the goal is to encounter a selection that can fend for itself, if the intent were to coddle the plants, I could simply plant and protect subtropical cultivars.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on March 28, 2019, 12:45:44 PM
What about working to design a microclimate. If you have a lot of land this may be possible. I saw one video where a guy in Montana excavated a small valley, made a lake at the bottom, with big boulders to help absorb and hold the heat, and then he could plant things on the South-facing terrace on the slope of the valley. The valley offered protection from wind, and being sunken into the earth created somewhat of a heat bank. The reflection of the sun's rays off the surface of the water also helped focus heat on the South-facing slope. This was in zone 5, but he said the temperatures at the bottom correlated to zone 7 or 8.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 28, 2019, 01:01:41 PM
I don't have the deep pockets required, but if a naturally occurring site as you describe were glazed it should definitely be possible. It probably could work on either a small, or large scale.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2019, 11:55:06 AM
Here are some somewhat clearer photos of 2 hardy F2 citranges. Most of the rows have been inspected and there will not be many more normal sized findings. There are numerous dwarf plants that don't show much damage. These F2 plants are surrounded by dead F1 plants.

Bottom focused photo.
(https://i.postimg.cc/JstGKwqF/Mar-30-2019-F2.jpg) (https://postimg.cc/JstGKwqF)
Top focus
(https://i.postimg.cc/njNy8mb7/Mar-30-2019-B.jpg) (https://postimg.cc/njNy8mb7)
Bottom focus
(https://i.postimg.cc/v1fq1Np1/Mar-30-2019-C.jpg) (https://postimg.cc/v1fq1Np1)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 30, 2019, 07:15:23 PM
I wonder what is a  number of F2 that are still green now?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2019, 07:32:04 PM
Ilya, there are perhaps a bit over 20 hardy dwarfs, which have limited potential. In regards to the normal sized plants, there are realistically only about 10. There are several that are brown on top and green at the bottom. At present there should be no additional new damage occurring, however I'm reluctant to give a solid number until new growth begins.
Poncirus flower buds are beginning expansion, vegetative buds are still not showing any expansion. I suspect the F2s will begin growth approximately when the Poncirus does.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 31, 2019, 04:02:14 AM
Ilya, there are perhaps a bit over 20 hardy dwarfs, which have limited potential. In regards to the normal sized plants, there are realistically only about 10. There are several that are brown on top and green at the bottom. At present there should be no additional new damage occurring, however I'm reluctant to give a solid number until new growth begins.
Poncirus flower buds are beginning expansion, vegetative buds are still not showing any expansion. I suspect the F2s will begin growth approximately when the Poncirus does.

I began with an initial population of 20,000+ seedlings. The seedlings are 85% nucellar and 15% zygotic, so the effective population under trial  is 3,000 plants.
[/url]
Thank you, I guess even dwarfs are worth to keep and later graft on poncirus. I have several hybrids that are growing much better on strong roots.
Have you started with 20000 seeds or 20000+ is an estimated number of seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2019, 04:14:48 AM
It's an estimate, I simply took 4,200 seeds per liter mutiplied by 5 liters of seed. I didn't physically count the trees.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 31, 2019, 03:04:09 PM
I'm wondering what you have against the dwarfs.  Dwarfs of many fruits are popular.  To me, surviving a winter would make them treasures.  Do dwarfs in citrus not do well?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2019, 03:19:49 PM
Walt, I assume they will take longer to get to the point of fruiting, and be slower to replace any growth lost to cold damage. Perhaps the fruit might be miniaturized. Once mature, they may be fine. I guess I have a preference for strong, vigorous growth.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 01, 2019, 02:13:23 AM
If they are dwarf because they just grow slower, then I can agree, though I repeat that having survived your winter they are worth having and breeding them.  But if they are dwarf because their internodes are shorter thyn may not be slow maturing.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 08:06:54 AM
Good point, Walt. I am obviously not going to discard any of the surviving plants. I'm evaluationg what I assume they could contribute toward the goal of extreme cold hardy citrus. And I agree that their genetics should be valuable, as their progeny likely will carry hardiness when crossed with full sized specimens.
Poncirus vegetative buds have just started to swell the least bit and I expect the surviving hybrids to follow suit shortly. That will bring a moment of truth to this venture.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 10:57:34 AM
Poncirus leaf buds have just started to swell the least bit and I expect the surviving hybrids to follow suit shortly. That will bring a moment of truth to this venture.

So the hybrids are breaking dormancy later than P. trifoliata.  That would be a good trait here, where late spring freezes are common.
Unless the hybrids are breaking late due to some cold damage.
 I am learning a lot from your experiment.  Thank you for sharing all this.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 11:54:01 AM
This is an educational experience. I am impressed by the broad range of characteristics the F2 .progeny are displaying. I don't regret the large population grown. If there is ultimately one hardy seedling per two thousand plants, it should be roughly reproducible on a repeat test under similar conditions.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 02, 2019, 12:03:37 PM
"it should be roughly reproducible on a repeat test under similar conditions."

If done in a zone 7 environment there should be even more survivors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 02, 2019, 12:14:36 PM
Mikkel,
I wonder if you can share your experience if any  on ~500 N1tri seeds that I sent you last autumn?
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 02, 2019, 02:03:03 PM
I will. By now the tallest are around 10 cm high. There are others beside still just germinating.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 02:16:43 PM
Using US 852 seedlings, with 60-70% zygotic seedlings would be good.  I might try to buy Stans whole crop next year.  From 14 fruit this year I got only 50 seedlings,  If I had sterilized the seeds, I might have had over 288.  As Ilya said, this has been a learning experience.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 07:02:52 PM
Walt, I am becoming suspicious that emerging and newly emerged seedlings exposed to low temperatures can develop leaf yellowing and stunting. I had a batch of TaiTri seedlings that had a late emerging seedling among more mature seedlings. This plant developed yellow leaves, has a green stem, therefore is likely stunted at least temporarily, but not an albino. Albinos will have the same stem and leaf color.
This may be related to SoCal's experience of exposing young seedlings to low temperatures and having the seedlings develop yellowing leaves. It is possible to cold -injure immature plants without downright freezing them. I have no concerns with introducing even recently emerged seedlings outdoors if the temperatures are high enough.

When the seedlings achieve 3"-3 1/2" in height I've put them outside in the 60's F., providing it's sunny and calm.


Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on April 02, 2019, 09:27:25 PM
Where I am (Olympia, WA zone 8a) I've found that it is not really safe to bring citrus seedlings outside (even hardy varieties that have been growing inside) until the second half of March.
It is different in different places. Places like Minnesota and Massachusetts can have later Spring frosts.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 11:10:20 PM
I expect to have to carry my plants inside a few times.  Yjey won;'t be safe for another 5 weeks.  But they need to get used to the sun gradually.  Wind too.  Basicly I'll treat them like tomatoes.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 03, 2019, 02:07:52 AM
Walt, I am becoming suspicious that emerging and newly emerged seedlings exposed to low temperatures can develop leaf yellowing and stunting. I had a batch of TaiTri seedlings that had a late emerging seedling among more mature seedlings. This plant developed yellow leaves, has a green stem, therefore is likely stunted at least temporarily, but not an albino. Albinos will have the same stem and leaf color.
This may be related to SoCal's experience of exposing young seedlings to low temperatures and having the seedlings develop yellowing leaves. It is possible to cold -injure immature plants without downright freezing them. I have no concerns with introducing even recently emerged seedlings outdoors if the temperatures are high enough.

When the seedlings achieve 3"-3 1/2" in height I've put them outside in the 60's F., providing it's sunny and calm.

60degree F. sunny calm weather (5 hours)
(https://i.postimg.cc/hhnL0swq/Tai-Tri-seedlings-April-2019.jpg) (https://postimg.cc/hhnL0swq)

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 06, 2019, 04:42:40 PM
Some of the F2 seedlings have just begun to push buds today. It's barely noticeable, should become more obvious over the next 3 days as warm weather is in the forecast. I'll attach a photo, the expanding bud is on the upper right side of the stem. Now it becomes a wait and see game to see how many will grow.
(https://i.postimg.cc/2VpQvG0L/April-6-2019.jpg) (https://postimg.cc/2VpQvG0L)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 08, 2019, 03:52:03 PM
Photos showing the impact -11.8 deg F. had on Poncirus at this 6b location. Mature growth is fine, immature growth is being sorted out between tip die back and new growth stimulus from the roots. The damaged fall growth demonstrates the result of the sub-zero temperatures suffered at the end of Jan - beginning of Feb.

 The remainder of the photos are examples of hardy dwarf F2 citranges.
I'm favorably impressed by the cold resistance performance of a very few of the F2 population in comparison with Poncirus. Granted, there is a very low percentage, but the concept appears to be valid. Fruit edibility of the hardy specimens is quite another hurdle indeed!

Poncirus winter damage
(https://i.postimg.cc/wyw62kQS/Apr-8-2019-G.jpg) (https://postimg.cc/wyw62kQS)

(https://i.postimg.cc/njSJBhHx/Apr-8-2019-H.jpg) (https://postimg.cc/njSJBhHx)


Various dwarf F2 Citrange survivors
(https://i.postimg.cc/Nypqvj2X/Apr-8-2019-I.jpg) (https://postimg.cc/Nypqvj2X)

(https://i.postimg.cc/dDzMYX35/Apr-8-2019-A.jpg) (https://postimg.cc/dDzMYX35)

(https://i.postimg.cc/nXJ6sDv7/Apr-8-2019-B.jpg) (https://postimg.cc/nXJ6sDv7)

(https://i.postimg.cc/TprsX3ZP/Apr-8-2019-C.jpg) (https://postimg.cc/TprsX3ZP)

(https://i.postimg.cc/HrdhWCg9/Apr-8-2019-D.jpg) (https://postimg.cc/HrdhWCg9)

(https://i.postimg.cc/5YhsZhgv/Apr-8-2019-E.jpg) (https://postimg.cc/5YhsZhgv)

(https://i.postimg.cc/tYtBMmxZ/Apr-8-2019-F.jpg) (https://postimg.cc/tYtBMmxZ)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 12, 2019, 12:06:42 PM
After cutting the plants down low to the ground I was able to get a better count on the number of survivors. There should be 12 normal sized survivors, they are not all equals, some lost more stem than others. Counting even the smallest dwarfs, there are about 66 dwarf survivors. Many of these are not very impressive due to low vigor. The flags were used last summer to identify zygotic seedlings, they're no longer of much value.

(https://i.postimg.cc/t7NVSMf7/cut-plants-Apr-12-2019.jpg) (https://postimg.cc/t7NVSMf7)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 13, 2019, 09:45:06 AM
Due to the fact that the dead citrange tops have been cut off, I was able to weed the 4 rows of plants this morning. Ilya had mentioned that some of the plants would regrow from the roots. I had dismissed that possibility as each time I canvassed the plants their condition had declined further. That's no longer the case, as some plants I had dismissed as doomed are growing from a lower stem point.

So, I need to categorize the remaining plants into at least 3 categories: normal sized and stem hardy above the snow line, dwarf and hardy (likely under the snow), and normal sized, but only stem hardy under the snow during our sub-zero temperatures. As they grow out, the stem position where the new growth originates will show how stem hardy the plant was.

Unless the plants regrowing from low positions are unique in some way (monofoliate, etc.) they might not be included in the elite group of super hardy specimens for further breeding. They do warrant preservation and further evaluation, however. They might be better suited to zone 7 growing conditions.

I assume that the F1 hybrids are dead, and the under-snow hardy plants are F2 plants.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 13, 2019, 07:46:36 PM
As soon as your trees have leaves, you might taste them as Ilya does.  It would be great if even one lacks the Poncirus taste.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 13, 2019, 08:05:38 PM
Great idea Walt, even a second tier hardiness specimen would be of value if it had improved taste.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 17, 2019, 12:55:23 PM
A few monofoliate dwarf F2 plants. Low vigor, hardy under snow.
(https://i.postimg.cc/Dm2Fd2PZ/Monofoliate-dwarf-1.jpg) (https://postimg.cc/Dm2Fd2PZ)

(https://i.postimg.cc/PpdG44Zc/Monofoliate-dwarf-2.jpg) (https://postimg.cc/PpdG44Zc)

(https://i.postimg.cc/0rWgY7NW/Monofoliate-dwarf-3.jpg) (https://postimg.cc/0rWgY7NW)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 20, 2019, 04:12:09 PM
Today I cross-pollinated my HRS 899 Variety which I got from Bernhard Vosss years ago (letter I don't know) with pollen of Citrus Lemonade, a vareity of New Zealand which tastes like sweet  Lemon imonade ;-) I will see what will happen.
(https://i.postimg.cc/9wBXnJqW/DSC00324.jpg) (https://postimg.cc/9wBXnJqW)

(https://i.postimg.cc/mzfbZ0YL/DSC00325.jpg) (https://postimg.cc/mzfbZ0YL)

(https://i.postimg.cc/4nRv7Psn/DSC00326.jpg) (https://postimg.cc/4nRv7Psn)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 20, 2019, 04:30:52 PM
Usirius, It's impressive how strongly the phenotype in the flowering branches resemble Poncirus! How hardy have you experienced it to be?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 01:16:53 AM
Kumin, yes if one do not know that  this is a HRS 899 F2 and would see an not flowering twig one would surely say that this is surely no poncirus hybrid....Only th flowers Show a Little difference to poncirus flowers, - one is the bigger stalk between flower and twig and another is that flowers can also accur on Little fresh growing twigs and not also directly at a brunch bud. My experiences of hardiness is -17C nin plein air without any damages. I did not have colder winters therefore I cannot say if it is also more hardy. But my hope is, if you take this instead of Poncirus as hybridization partner, on the one hand the good frost-hardness predisposition and on the other hand instead of a few bad poncirus genes a few genes of the Changsa mandarins, which are also included in the new hybrid....
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 22, 2019, 04:10:42 AM
Usirius,
Are you sure that it is not a poncirus rootstock that took over the HRS graft?
As I remember all HRS899 seedlings of B.Voss are evergreen.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 01:21:58 PM
Usirius I couldn't remember if Poncirus flowers had a flower stalk. Since mine are in full bloom at present, I took a look at them and was surprised to see them vary from almost no stalk to a short stalk. The flowers with a stalk had fuzzy hairs on the stalks (pubescense). If your tree is a hybrid indeed, it appears to have retained many Poncirus characteristics. This should prove helpful in achieving winter hardiness. My cellphone doesn't take very good macro shots, or I'd attach several.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 04:29:57 PM
Kumin, interesting that your Poncirus varies from almost no stalk to a short stalk. My poncirus Show on all flowers nearly no stalk. My HRS 899 is indeed a hybrod which includes many viewable poncirus characteristics. Also the fruit show also haurs on its skin, but the shape is more like a pear, see my post of Januray this year: http://tropicalfruitforum.com/index.php?topic=30863.0 (http://tropicalfruitforum.com/index.php?topic=30863.0)  Tomorow I will smell at the flowers whether they smell otherwise than poncirus flowers do.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on April 22, 2019, 04:37:19 PM
Don't think this is 899. Ihave four of them and none of them has flowers like the ones you show. They look like PT-flowers. I had an early blooming PT "Kryder" that produced Flowers with pink stamens.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 05:16:41 PM
My one is one of several HRS 899 seedlings selections from Bernhard Voss.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 05:42:42 PM
Usirius, the pink stamen color looks very similar to the pink leaf parts on your fruit photo. I have seen a bit of reddish color in autumn, but never such a distinct pink on my trees.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 06:14:06 PM
The deep green F2 hybrids are breaking buds at present. All of them were later than Poncirus. Temperatures obviously play a role on timing, but overall they are 10-14 days after Poncirus. In both Poncirus and the F2 hybrids, any tissue that's olive-green rather than deep green is compromised and struggles to break buds and begin to grow. In most cases the upper stem may fail to bud out, but the lower stem will bud out. The winter we've just come through wasn't the coldest I've seen, but probably in the 75 percentile.

Olive green branches struggle to begin growth (Poncirus)
(https://i.postimg.cc/B8ZSZtpb/PT1.jpg) (https://postimg.cc/B8ZSZtpb)

(https://i.postimg.cc/Wtq21BGG/PT2.jpg) (https://postimg.cc/Wtq21BGG)

(https://i.postimg.cc/CB3p8KGj/PT3.jpg) (https://postimg.cc/CB3p8KGj)

It's amazing any segentranges survived, considering the extent of damage Poncirus shows.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 23, 2019, 07:18:48 AM
Here are 2 photos of plants I had potted up in March. These are advanced further than the ones that remain field planted. The new growth is fairly vigorous. Conestoga # 001

(https://i.postimg.cc/cgQ3Fkbg/a-April-22-2019.jpg) (https://postimg.cc/cgQ3Fkbg)

This plant doesn't appear to be particularly thorny. Photo was taken at sunrise. Conestoga # 002
(https://i.postimg.cc/F7FPJ0Yg/April-22-2019.jpg) (https://postimg.cc/F7FPJ0Yg)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 23, 2019, 01:27:36 PM
Kumin,
thank you for sharing your experiences with Segentranges versus Poncirus trifoliata and also for the really impressing pictures.
I also have seen that segentranges show a longer period of winter rest than PT itself. Also Poncirus polyandra in plain air and also in greenhouse (!) stay for about 14 days longer in dormancy than Poncirus trifoliata  - can be compared with the Segentranges.
Today I put my nose to the flowers of my HRS 899 segentrange and I would sy it smells a little bit more than Poncirus trifoliata flowers do. The HRS 899 segentrange flowers are also larger than those of my Poncirus trifoliata. My Poncirus trifoliata does only show slightly pink coloured Stamens. The one HRS 899 Sgeentrange which I have is the only one which survived in 17 years. I had several phenotypes but one after the other died in the first winters. And this one which I described here survived without any damages for such a Long time. Also it survived more times early beginning of spring with  following night freezes - whew my poncirus got slightly damaged in some years. So I would propose ist hardiness is due to longer dormancy better than this of Ponirus trifoliata.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 24, 2019, 05:35:24 AM
It's interesting that Poncirus polyandra shows a bit of similarity to citranges. P. polyandra isn't considered to be a Citrus- Poncirus hybrid, but either a sister species to P. trifoliata, or perhaps ancestral to it. In some aspects it's apparently intermediate between Citrus and P. trifoliata, or perhaps closer to Citrus than P. trifoliata is.
Having suggested this, I have no experience with P. polyandra, and haven't seen it.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 24, 2019, 07:03:53 AM
It is way less winter hardy than P.t.. I had diebacks at -6C at least it recovered. Usirius how is yours? Is hardy it in open ground for you?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 24, 2019, 04:53:47 PM
kumin,

if I would not know that is really Poncirus Polyandra I would say that is a Citrange. The Habitus and the foliage is very similar most types of Citranges. I am still waiting for flowers and fruits. As far as I have seen there are two phenotypes....othe ne with larger foliage and the other with clearly smaller foliage.

mikkel,

I think it is more hardy than -6C. During longer enduring periods of frost I cover it with a rug - and if temperatures go down in the night below -10C I heat with a 5 W lamp. This is enough - may be this effort is more than necessary - because it did not show any damages accoridng this treatment through all the years.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 25, 2019, 02:36:34 AM
@usirius okay. This encourages me to give it another try.
Do you have any picture of the two types you spoke of?
I know of a plant in a botanic garden in Germany and another one in a private collection which is already flowering. But I haven`t heared of fruits so far. No idea if these are the same plant.


Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 03:18:09 AM
mikkel

I did not see the other plants you named. Maybe they all have the same origin.
By the way it is possible to post one or two photos which show the leaves of both phenotypes in the next days.
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 25, 2019, 06:47:58 AM
Mine flowers every year but never gave a fruit.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 25, 2019, 12:57:00 PM
Here's a photo of the best citrandarin of a Clementine X Poncirus F1 hybrid I grew from pollination to fruiting several decades ago. I eventually left it exposed to low winter  temperatures and promptly lost it. I sent 2 scions to a cold hardy Citrus enthusiast, Major C. Collins in Tifton, GA, but doubt that he propagated it as he had health issues, including vision impairment. I strongly regret losing this tree. It's hardiness was not remarkable.

This fruit was tart, with mandarin flavor and excellent color. The peel had faint Poncirus scent, the fruit had almost no off flavors, but was as tart as an unripe mandarin.

(https://i.postimg.cc/CRbqrGG9/Citrandarin-a.jpg) (https://postimg.cc/CRbqrGG9)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 04:34:03 PM
kumin,

thank you so much for sharing this wonderful story with us. Although it is a pity that you have lost this particular hybrid, it encourages one to try your own crossbreeding attempts! - Years ago I read that it would be impossible to cross Poncirus trifoliata with Citrus ichangensis with Poncirus as mother. I thought, it doesn't work, it doesn't exist and had put it in my head to breed the citrus lucky clover leaf! And lo and behold, I have managed the pollination and the fruit has developed and from the few seeds has developed a clear hybrid, I have then almost the same mistake as you, I have planted the plant because it became too big for me and I thought it would immediately survive the next winter without protection. It came what had to come, it became a hard and very cold winter and the plant broke down, but before I had cut branches and made graftings, only these did not develop as beautifully as the mother plant! I didn't take care of it as much anymore...out of disappointment as it happened.  - Now I try to hybridize the HRS899 Segentrange with Citrus Lemonade. The Citrus Lemonade is a hybrid Citrus limon x reticulata and ist fruits  have a wonderful Aroma - it taste like a good tasting Lemonade. Here are some pictures of my HRS899 Segentrange - branches and flowers, I have cut it down last winter mercilessly this year because it is very vigorous and flowers relatively little. Here are some recent pictures of the leaves and flowers, also of the thorns. You can compare the habitus with your Poncirus varieties!
(https://i.postimg.cc/RqfYqcYH/DSC00617.jpg) (https://postimg.cc/RqfYqcYH)

(https://i.postimg.cc/vcsNn4RS/DSC00619.jpg) (https://postimg.cc/vcsNn4RS)

(https://i.postimg.cc/gwQM2Jqs/DSC00620.jpg) (https://postimg.cc/gwQM2Jqs)

(https://i.postimg.cc/sMfHnbgY/DSC00621.jpg) (https://postimg.cc/sMfHnbgY)

(https://i.postimg.cc/0Kqc7B4J/DSC00622.jpg) (https://postimg.cc/0Kqc7B4J)

(https://i.postimg.cc/PC630KCB/DSC00623.jpg) (https://postimg.cc/PC630KCB)

(https://i.postimg.cc/KkT0k202/DSC00624.jpg) (https://postimg.cc/KkT0k202)

(https://i.postimg.cc/T5qQ0c8N/DSC00625.jpg) (https://postimg.cc/T5qQ0c8N)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 04:51:42 PM
Sylvain,
interesting that also flowering is no sign for fruting! I never have seen fruits from it - also no pgotos from it. Enclosed there are some pictrues which show the two phenotypes that are existing according to my knowledge - the small leafed and the large leafed one. Which one do you have in culture?
(https://i.postimg.cc/xqBVkfgX/DSC00626.jpg) (https://postimg.cc/xqBVkfgX)

(https://i.postimg.cc/JtsW4D3w/DSC00627.jpg) (https://postimg.cc/JtsW4D3w)

(https://i.postimg.cc/dk1cCDzy/DSC00628.jpg) (https://postimg.cc/dk1cCDzy)

(https://i.postimg.cc/k2QC30QB/DSC00629.jpg) (https://postimg.cc/k2QC30QB)

(https://i.postimg.cc/s1Lsp9fD/DSC00630.jpg) (https://postimg.cc/s1Lsp9fD)

(https://i.postimg.cc/625thMGT/DSC00631.jpg) (https://postimg.cc/625thMGT)

(https://i.postimg.cc/GHsrz89P/DSC00632.jpg) (https://postimg.cc/GHsrz89P)

(https://i.postimg.cc/SnCSQ2hQ/DSC00633.jpg) (https://postimg.cc/SnCSQ2hQ)

(https://i.postimg.cc/ZvWmG0HS/DSC00634.jpg) (https://postimg.cc/ZvWmG0HS)

(https://i.postimg.cc/gwGWYgs4/DSC00635.jpg) (https://postimg.cc/gwGWYgs4)

(https://i.postimg.cc/rdT8DVV1/DSC00636.jpg) (https://postimg.cc/rdT8DVV1)

(https://i.postimg.cc/G8rHnPT1/DSC00637.jpg) (https://postimg.cc/G8rHnPT1)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 25, 2019, 05:09:51 PM
Mine looks like the one on the 4th picture. It comes originally from BG Darmstadt.
I just tried to find the pictures of the flowering plant  to see if it is different but I can not find the link. Maybe later...
usirius do you have both types?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 25, 2019, 07:31:19 PM
Beautiful pictures, the petioles are quite elongated. The entire leaf has a pointed, longer aspect. P.trifoliata has a shorter, blunter look to the leaves. One of my citranges superficially had some resemblance to these photos.
(https://i.postimg.cc/rzH4y70p/IMG-20180811-154404.jpg) (https://postimg.cc/rzH4y70p)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 09:27:35 AM
Mine looks like the first and last picture. It comes from Horst.
The folioles are very thin.

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/Poncirus%20polyandra%20fleur3.jpg)

And this is a drawing of the original plant:

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/poncirusPolyandra.jpg)

We can see that the one with thin leaflet is the right one. The other could be a hybrid.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 26, 2019, 10:17:22 AM
Found the link: This is the plant from Horst. The same as Sylvains.

http://yuccaundanderefreilandsukkulenten.xobor.de/t1071f9-Erstbluete.html (http://yuccaundanderefreilandsukkulenten.xobor.de/t1071f9-Erstbluete.html)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 26, 2019, 10:37:29 AM
Usirius,
- Years ago I read that it would be impossible to cross Poncirus trifoliata with Citrus ichangensis with Poncirus as mother.
Last year just out of fun I  pollinated 7 castrated  Swamp Lemon Poncirus flowers with C.ichangensis IVIA358 pollen. Five fruits yielded 178 seeds, giving 224 seedlings. At least 64 of them were clear hybrids, with shape of their leaves intermediate between those of poncirus and ichangesis.

Now I try to hybridize the HRS899 Segentrange with Citrus Lemonade.

Strictly saying HRS899 seedlings from B.Voss are segendarins (second generation citrandarins), not segentanges ;D
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 26, 2019, 11:22:34 AM
Ilya11,

that sounds interesting what you did with crossing Poncirus and ichangensis also with success. So it is possible - against the things what I have read in litertaure many years ago. Did yiu have been able to have plants which Show leafes with four similar large parts ?

Yes and you are right.....the F2 generation of HRS899 are Segendarins!


Sylvain,

thank you for sharing the Picture of you. You mentioned my Picture No. 5 (not 4) ? So this is the larger foliated phenotype. The smaller foliated phenotype seem to be more frost hardy. Both phentotypes have been discovered many years ago in the Yunnan Region in China by a friend of me - and buddhist Monks told him that both are species of P. Polyandra. So I believe that there are Minimum  two phenotpyes existing. My friend did only see one fruit in rather grat tree. One aother intersting Thing is that the origin great trees Show succers at their roots!


mikkel:

thanks for the link for the picture. It Shows the larger foliated phenotype which I also have.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 26, 2019, 11:56:22 AM
Did yiu have been able to have plants which Show leafes with four simalr large parts ?
Not really, most have the smaller back side leaflets like this:

(https://b.radikal.ru/b20/1904/a0/a9ff96052cfa.jpg) (https://radikal.ru)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 12:16:16 PM
I said "first and last picture." that is #1 and #12.
#4 is ok too but not #5.

You can read more here:
http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic123-15.html (http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic123-15.html)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 12:24:28 PM
Error, sorry.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 26, 2019, 04:13:22 PM
Ilya11,

thank you for the picture of your crossing. I will show you a picture of mine shich has more narrow leafes. The young leafes seem to grow to 4 similar leafes but during growing the relation between the three leafes and the stalk gets different.

Sylvain,

thank you for clarifiying - sorry this has been my error.
Nevertheless I believe that yours seem to be the larger foliated phenotype?
Can you please measure on some typical leafes the length of  the middle leave and let me know?
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 27, 2019, 08:52:04 AM
Here it is:

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/Poncirus_Polyandra_leaf.jpg)

Leave 8.7 cm, middle leaflet 6.3 cm, petiole 2.4 cm, lateral leaflets 2.6 cm and 4 cm.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 02, 2019, 01:03:11 AM
Ilya11,

enclosed two pictures of young leafes and one picture of one adulte leafe of my crossing -  most other adulte leafes are lost during winter:

(https://i.postimg.cc/ZByhYqSp/DSC05785.jpg) (https://postimg.cc/ZByhYqSp)

(https://i.postimg.cc/Y4PHwWJt/DSC05786.jpg) (https://postimg.cc/Y4PHwWJt)

(https://i.postimg.cc/K1ZF7FPh/DSC05787.jpg) (https://postimg.cc/K1ZF7FPh)

sylvain,

thank you for picture, it seem so that you have the same large leafed P.P. I also have - you can see this on the following two pictures of my plant


(https://i.postimg.cc/wRHbKxT6/DSC05789.jpg) (https://postimg.cc/wRHbKxT6)

(https://i.postimg.cc/672Pn1mN/DSC05790.jpg) (https://postimg.cc/672Pn1mN)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 02, 2019, 04:16:41 AM
Usirius,
Your hybrid has very few  features from papeda. Petiole and the proportion of adult leaflets are very close to those of poncirus. What clone of C.ichangensis have you used?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 03, 2019, 03:05:01 AM
Ilya11, I took the pollen from a Citrus ichangensis which I purchased ad nursery Otto Eisenhut in San Nazzaro (Suisse) many years ago. Otto Eisenhut propagated C. ichangensis from a ichangensis-tree of Dr. E. Frey. This tree of Dr. E. Frey survived planted decades of years in plein air without any protection in a garden in Ronco s/A close to Lago Magiore. So it is not a special cultivar but one which has shown a good frost resistance all the yeras in - I would say USDA zone is between 8 and 9.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 03, 2019, 04:31:07 AM
Thank you Usirius,
Eisenhut currently has three clones of C.ichangensis: Clone "Klock" (Z269), IVIA (Z189 ) and Z83 which is marked as exceptionally frost resistant.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 03, 2019, 10:35:29 AM
Ilya11,
thank you for update concerning Eisnhut portfolio. I bought my C. ichangensis for about 25 years ago, in this time Eisenhut only had the one C. ichangensis variety from which I took the pollen for sale. I think that this one is the Z83. Klock did in this time no material exchange with EIsenhut. And the IVA Clone found its way to Einsehut earliest I would say 10-15  years ago.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 03, 2019, 11:43:47 AM
I bought my first C.ichangensis from B.Voss in 2001, it was listed as N2 (resistant to -12C) and originated from Florida arboretum. I believe O.Eisenhut and B.Voss exchanged many varieties at this time. I lost this plant after a warm winter followed by late spring frost of -9C.
Do you still have your original  Eisenhut ichangensis?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 04, 2019, 07:56:09 PM
Here are current photos of the F2 segentranges. A few are from plants potted in March, but most are from plants still in ground at present. Except for the small seedlings, the remainder have survived -11.8 deg F. in Jan/Feb of 2019. The shorter plants had some natural protection provided by snowfall.

A vigorous, deciduous specimen. No protection provided at any time. Conestoga # 011
(https://i.postimg.cc/0r8C1C5N/May-4-2019-a.jpg) (https://postimg.cc/0r8C1C5N)

A unique plant that had zero dieback, not especially vigorous (small leaves). This plant was clearly taller than the snow cover.
(https://i.postimg.cc/QVxcyxS9/May-4-2019-b.jpg) (https://postimg.cc/QVxcyxS9)

2 fairly vigorous specimens.
(https://i.postimg.cc/nMP9SKCg/May-4-2019-c.jpg) (https://postimg.cc/nMP9SKCg)

The large pots are F2 hybrids potted in March, the remainder are 2019 seedlings of several cold hardy selections.
(https://i.postimg.cc/JswDM13Q/May-4-2019-d.jpg) (https://postimg.cc/JswDM13Q)

A vigorous F2 unprotected specimen.
(https://i.postimg.cc/VSmJ0DVr/May-4-2019-e.jpg) (https://postimg.cc/VSmJ0DVr)

2 additional specimens.
(https://i.postimg.cc/k6hGZ9XK/May-4-2019-f.jpg) (https://postimg.cc/k6hGZ9XK)

There are quite a few more small surviving plants that are less photogenic. Within a month I hope to begin grafting some of most mature specimens unto P. trifoliata.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 05, 2019, 04:15:07 AM
Congratulations!
Actually you have been lucky to have such extreme winter for a rapid selection.
I am rather upset with the absence of real cold this season, too many seedlings are still alive ;D
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 05, 2019, 07:02:13 AM
It's interesting you mention having too many survivors due to inadequate cold to eliminate marginally hardy plants. As I explain my goals to people in my community, the majority tell me "what a shame so few survived" not realizing the objective is to eliminate all but the very hardiest specimens. Some get the long version, and others get the short version, in the explanation of the details.

I have a family member that lives 200 miles south of me in zone 7b. I may trial clones of some of the better F2 specimens to see the results in that area.

The winter has indeed been severe, affecting local Kaki persimmons severely, delaying leaf emergence, and, or actual killing established trees.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 05, 2019, 10:54:34 AM
kimon,

thank you for sharing the result of the nseleciton. I agree fully to Ilya11 and you that main objective it to select only those specimens who survive properly also in very stron winter seasons. In the past I selected specimens of Citrange and Segentranges surviving some yeras with less to no damage and than they died in an more extreme winter - at -17C or at .20C which U already had here. And some died after surviving such an extreme winter after being awake by a slight night freeze....... So all thos specimens are worthless and as more early as one can find out this one is able to concentrate the work on few seedlings and onbe also has again room for testing new prduced hybrids. I can confirm your experience - that in winters which damaged my  kakis also many citrus selections of mine has been damaged, so I think that Kaki (also Trachycarpus, Olea, Pistacia....) damages can be used as well sign concerning finding out well surviving citrus specimens. Only Problem may be I think that those specimens have a grater part of poncirus - also regarding fruit properties.

Ilya11,
know the Problem you have....also here since I would say 5 years we did not have a very hard winter any more. Well on the one side...my kakis and other exoctic plants lile Trachycarpus, Pistacia. Olea ....show no damages so Long. Good for the development of the individual plants...bad for knowing more alate which specimens are not worthy to keep them in the future.

To your question concerning C. ichangensis....I did not keep itbecause of its weak fruit quality.
.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 05, 2019, 12:46:13 PM
Completely agree with Usirius that each winter presents different challenges for citrus resistance.
Basically still, there are two different scenarios: gradual late autumn cold acclimatization followed by either a dry freeze or a moist heavy snow.
The third challenge is a late winter/spring rise of temperatures broking dormancy  followed by an abrupt freeze.
Fully hardy hybrids other than having an ability to resist extremely low  temperatures and  burn by snow should have a very deep dormancy to avoid an abrupt winter return.
 
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 02:34:46 PM
To your question concerning C. ichangensis....I did not keep it because of its weak fruit quality.
I think C. ichangensis may have much value for hybridization because it's the only fruit that does not have poncirus bitterness and is still fairly cold hardy. If you crossed it with something like citrange you might get something useful.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 05, 2019, 03:33:43 PM
SoCal, I have several years to plan where to go from this point. I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime. Any potential pairing of parents should offer either increased hardiness, or edibility. Hardiness is becoming apparent in the F2 survivals, but  palatability is unproven. I don't plan on re-introducing tender Citrus from this point forward. Therefore improvements in flavor would need to come from the very hardiest non-poncirus sources as you suggest, or from genes within hybrid populations. After the plants grow additional foliage, I will be able to taste-test them for Poncirus off-tastes as Ilya does.

If I'm very fortunate a few of the plants might have edible fruit. In the past when I created Citrandarin hybrids, there was one edible (albeit sour) individual in the first generation. My understanding is that having mandarin parentage dramatically reduces the Poncirus off-flavors. Ruby blood orange, as the Citrus component of these F2 citranges likely won't provide such a benefit.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 03:48:52 PM
If I'm very fortunate a few of the plants might have edible fruit.
Hybridizing very hardy citrus that is truly good eating quality is going to take a long time.
I would count yourself lucky if you are able to achieve a hybrid that can survive in your winters and doesn't have poncirus bitterness, even if it might not be good fruit quality.

Perhaps someone in the future could later take your achievement and use it to hybridize a better hybrid in the future.
Incremental progress. If you achieve a significant improvement, even if it might not be what you had hoped for, don't throw it away.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 04:05:34 PM
I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime.
There's no chance Citrumelo is going to survive for you in 6b. TaiTri might.

I do think Citrumelo is, generally, just a bit hardier than Citrange, but you are going to need a lot of seedlings to show any that exhibit exceptional hardiness, similar to the citrange trial you have already carried out.

Considering that you are in 6b, I could see the reluctance to use C. ichangensis in hybridization. Even C. ichangensis simply isn't hardy enough where you are.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 07, 2019, 09:04:05 AM
One of the surviving Segentranges has ragged edged central leaflets. They vary a bit, but are generally notched and have uneven leaf tips. This is one of the more vigorous plants, hopefully the asymmetrical leaves won't won't be matched with asymmetrical flowers. In my previous work on citrandarins there was some correlation between leaf and flower symmetry. A few had petaloid anthers in the flowers.
(https://i.postimg.cc/CB0X81fN/Notched-leaf.jpg) (https://postimg.cc/CB0X81fN)
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on May 12, 2019, 03:28:53 PM
If I'm very fortunate a few of the plants might have edible fruit.
Hybridizing very hardy citrus that is truly good eating quality is going to take a long time.
I would count yourself lucky if you are able to achieve a hybrid that can survive in your winters and doesn't have poncirus bitterness, even if it might not be good fruit quality.

Perhaps someone in the future could later take your achievement and use it to hybridize a better hybrid in the future.
Incremental progress. If you achieve a significant improvement, even if it might not be what you had hoped for, don't throw it away.


As always, we have similar goals but are using different methods.  So far you have guessed right more than I have.  I have learned much from your results and modified my plans for the better.  Many thanks.

That said, I will be bringing in new breeding stock of pure citrus. 

I'll use Flying Dragon X Seedless Kishu.  Flying Dragon as it is my oldest P. trifoliata that gives a good percentage of zygotic seeds.  Seedless Kishu for its dominant gene for seedless.

I want to use Flying Dragon X Blood oranges.  Blood oranges have been said ,elsewhere on this forum, to have no sourness.  While I want some sourness in my citrus  fruit, all my 1/2 and 1/4 Pt hybrid fruit are much too sour.  IF the "no sour" in blood oranges is due to a single gene, then F2 Flying Dragon x Blood might include no sour or less sour fruit.  I think that (Clem x tri) x Clem juice mixed with a no sour trifoliata hybrid juice might give a good drink.

Also, as I've said elsewhere, I'd like to remake all the citrus X P. trifoliata crosses using Laaz's precocious P. t and using P.t like Poncirus+.

If anyone has the trees to make any of these crosses, but no room to grow them out, make the crosses and I'll make room for the seedlings.  And I'll share budwood as soon as possible.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on May 12, 2019, 03:32:35 PM
SoCal, I have several years to plan where to go from this point. I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime. Any potential pairing of parents should offer either increased hardiness, or edibility. Hardiness is becoming apparent in the F2 survivals, but  palatability is unproven. I don't plan on re-introducing tender Citrus from this point forward. Therefore improvements in flavor would need to come from the very hardiest non-poncirus sources as you suggest, or from genes within hybrid populations. After the plants grow additional foliage, I will be able to taste-test them for Poncirus off-tastes as Ilya does.

If I'm very fortunate a few of the plants might have edible fruit. In the past when I created Citrandarin hybrids, there was one edible (albeit sour) individual in the first generation. My understanding is that having mandarin parentage dramatically reduces the Poncirus off-flavors. Ruby blood orange as the Citrus component of these F2 citranges likely won't provide such a benefit.


Sorry.  This was the quote that I meant to have in my post above.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 04:46:07 PM
One thing to contemplate is if truly hardy edible Citrus is developed for climate zone 6b, the initial threshold for palatability may be set rather low. There will be no competing cultivars, that situation will likely change if the first cultivars can be utilized in further crosses to improve and refine flavors. Developing the initial cultivar with acceptable fresh eating quality could get the ball rolling in this respect. At this point the theoretical, as well as practical upper limit for cold hardiness is found in P. trifoliata. I don't think this upper limit is likely to change as there isn't any close relative that can offer greater hardiness. At best, advanced kumquat crosses might genetically contribute prolonged dormancy.

Ilya has stated that Poncirus shows heterozygosity for cold hardy genes. Perhaps, an improvement in hardiness could be made by selecting for homozygosity for these factors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 12, 2019, 05:27:10 PM
If I will have the second wave of flowering of Poncirus+ trifoliata this summer, I could pollinate it with the pollen of acidless orange Gosset that I have.
Selection of hardy F1 citranges and crossing  between them  can  eventually give acidless hybrids without internal oils  closer to PT in winter resistance. It is a little bit out of my current goals so may be I can share the eventual  F1 seeds with you.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 06:20:37 PM
Great idea, Ilya, Poncirus has plenty of acidity to contribute to it's progeny.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 07:05:23 PM
I have been a bit less active in posting lately, as I have potted 130 Poncirus seedlings in preparation for propagation of the F2 seedlings.
One of the germinating seedlings planted several weeks ago snapped the stem off during emergence due to the cataphyllic leaves not releasing from the planting media.

The seedlings were in a humidity dome and the severed apical stem didn't desiccate. On an impulse I grafted it on a 6 year old Poncirus tree (fruiting for the first time). Due to chilly weather it hasn't grown much, but it's apparently succeeded. I have previously grafted newly emerged seedlings successfully. The less differentiated tissue appears to take rather well. These aren't grafts in the truest sense, the rootstock is prepared as for budding, the seedling scion is inserted as a thin sliver 1/16 - 1/8 inch (2.5mm). If I find time, I will try to take photos of the process at some point.

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 15, 2019, 06:33:39 PM
Here is one of the hardiest plants in the group of survivors. Although not the most vigorous plant, it is unique for several reasons. This plant is growing out to the tip, with no dieback. The upper third of the plant is thornless, which is unusual considering it's hardiness. I will be propagating and monitoring this plant closely, despite it's flaws. Getting extreme hardiness combined with low thorniness is one step in the right direction. I'm interested in it's fruiting behavior and qualities. This plant also exibits prolonged dormancy/delayed spring leaf emergence.

(https://i.postimg.cc/d7TDjdV5/5-15-2019-c.jpg) (https://postimg.cc/d7TDjdV5)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 15, 2019, 08:28:52 PM
You're probably already doing this, but I'd keep some extra cuttings in case an unusually harsh Winter kills everything outside.
The trial can move along a lot faster if spare cuttings are kept of each cultivar. One will be growing fast inside, while being simultaneously tested outside.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 15, 2019, 10:59:53 PM
There are 130 Poncirus seedlings prepared and waiting for budding/grafting in June. The more desirable plants will be cloned several times. I have a geodesic frame I plan on covering during the winter with film, using water as a heat sink. There should be no need for artificial heat, provided there's adequate insulation on the north side of the structure.

This building should serve as a repository for all the clones. There are a number of seedlings (TaiTri, citrumelos, etc. from this spring's new acquisitions,these need to be cold tested to earn a place among the F2 segentranges. My intention is to have secure backup of each clone on hand.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 16, 2019, 04:32:53 PM
There are 130 Poncirus seedlings prepared and waiting for budding/grafting in June.

how old are your seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 16, 2019, 04:39:45 PM
1 to 3 years old. I planted a few thousand additional seeds again this spring . I don't want to be short when I need them.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 17, 2019, 06:55:47 PM
That is a lot of planting. Why do you sow in November when you get the seeds then you have 90% germination rate. This year I am planning also to sow 1000 seeds.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 17, 2019, 08:52:40 PM
I used an easy method, in the end of March I gathered fruit that had fallen in the autumn/early winter. After soaking them in water and squeezing/manipulating the fruits, the seeds separated from the pulp. I disinfected the seeds with Sodium  hypochlorite, then rinsed them and planted immediately. Due to recent cool temperatures, seedling emergence has only been evident for the last week. Germination appears to be satisfactory.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 18, 2019, 12:02:25 PM
This is a newly emerged seedling grafted to a branch mature enough to fruit. This type of graft has worked well for me. The rootstock bark is cut downward about 3.5 cm long trying not to cut into the underlying wood. The scion is prepared by selecting a thin twig and slicing off the skin of the bark on both sides, trying to not remove more of the cambium than necessary(exposing, but not removing the cambium). (It could be phrased as shaving off the epidermis on the 2 sides at the contact points.) These grafts have performed very well for me, perhaps because of the extensive cambium contact. The parafilm doesn't serve any purpose at this point other than indicating the graft location. The actual graft is lower on the stem than the parafilm.
(https://i.postimg.cc/N9kYv2wx/IMG-20190518-115029.jpg) (https://postimg.cc/N9kYv2wx)

 Waiting until these stems are mature enough to use as scions. (https://i.postimg.cc/D4fhvfv3/IMG-20190518-115146.jpg) (https://postimg.cc/D4fhvfv3)

TaiTri seedlings growing nicely. (https://i.postimg.cc/Rqv4Qdcp/IMG-20190518-115210.jpg) (https://postimg.cc/Rqv4Qdcp)

Citrumelos coming along well. (https://i.postimg.cc/SJs4HK1W/IMG-20190518-115225.jpg) (https://postimg.cc/SJs4HK1W)

Surprise Magnolia grandiflora discovered growing under Poncirus. The first seedling in 22 years!  (https://i.postimg.cc/cr9xJ3t9/IMG-20190518-115256.jpg) (https://postimg.cc/cr9xJ3t9)
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 19, 2019, 04:11:43 PM
I used an easy method, in the end of March I gathered fruit that had fallen in the autumn/early winter. After soaking them in water and squeezing/manipulating the fruits, the seeds separated from the pulp. I disinfected the seeds with Sodium  hypochlorite, then rinsed them and planted immediately. Due to recent cool temperatures, seedling emergence has only been evident for the last week. Germination appears to be satisfactory.

I prefer sow them in the fall, by the time spring comes they are 8-10 inches high, this way you extend the season to one year more, because PT stops growing at the end of September. A hormone mechanisms tell him to go dormant. Sodium hypochlorite is toxic and might kill some seeds I use peroxide.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 20, 2019, 05:40:02 PM
Here is a clearer photo of the 40 cm tall F2 Segentrange with no dieback after a low temperature of -11.8 deg. F. (-24.3 C) in the end of January of 2019. This plant is slow to break buds. It has a number of faults, such as low vigor and very slender growth. I'm not finding much correlation between vigor and hardiness, perhaps the reverse. One benefit of vigor is quicker recovery from cold injury, but vigor doesn't appear to provide much initial protection. Although this plant has short thorns near the base, the upper level is thornless.

I may try to use this plant in further breeding, if it matures and flowers in a timely manner. The partner should probably be one of the most vigorous specimens available.
(https://i.postimg.cc/0b0yYzNB/No-dieback.jpg) (https://postimg.cc/0b0yYzNB)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on May 20, 2019, 09:28:42 PM
"Surprise Magnolia grandiflora discovered growing under Poncirus. The first seedling in 22 years!"

What variety is the parent?
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on May 21, 2019, 03:31:37 AM
Usirius, no, Bernhard has been a little bit out of Citrus in the last years. He has lost most of hir plants after a storm had damaged his greenhouse. I have spent some time with him last summer and last weekend I met him in Vienna at the "Wiener Zitrustage". I wonder what 899-variety you have. The rather hairy fruits look strange to me. I have 4 899-F2-hybrids but only with 2 of them I am sure about the correct marking. I have (for sure) 899A and 899J and (quite sure) 899F and (don't know) 899E or H. All are blooming. 899A has sweet, mandarin-like fruits. 899J did not bear fruits yet and the fruits of the rest are not edible.
899A is monofoliate, 899J aswell, F and H Show trifoliate leaves, but very few with the years.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 21, 2019, 04:24:08 AM
Hardyvermont, Edith Bogue is the seed parent. It's likely also the pollen parent, but there's a 24 Below tree nearby, that could be the pollen parent.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 25, 2019, 04:32:06 PM
I compare the severity of winter cold by the affect on various cold sensitive woody plant species. I have already mentioned this winter's damage on Kaki persimmons (2 severely injured back to the trunk and major branches, 2 killed outright) Bamboo, cold injured  to the ground , Mimosa, delayed growth, but not killed. Today, I cut down  my dead Crape Myrtle that hadn't suffered much injury in the past 12 years, or so.
These 4 trunks were killed to the soil level. These trees had winter top-killed in the past, but not in the last decade.
I previously mentioned the need to classify the F2 survivors into 3 categories:

1. Stem survival above snow level,

2. Stem survival within snow height.

3. Stem survival within snow height-dwarf.

I now need to add a 4th category: survival from roots below soil level. These are obviously less hardy, and will be observed for unusual or outstanding characteristics.

2018-2019 was the most injurious winter in at least a decade, as these crape myrtles were killed to the ground.

My oldest Poncirus tree and offspring are in the background.


(https://i.postimg.cc/vggVKhdg/Crape-Myrtle-dead-to-ground.jpg) (https://postimg.cc/vggVKhdg)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 25, 2019, 07:22:38 PM
I wonder what 899-variety you have. The rather hairy fruits look strange to me. I have 4 899-F2-hybrids but only with 2 of them I am sure about the correct marking. I have (for sure) 899A and 899J and (quite sure) 899F and (don't know) 899E or H. All are blooming. 899A has sweet, mandarin-like fruits. 899J did not bear fruits yet and the fruits of the rest are not edible.
I have a few seedlings of US 852 as well, so I'm assuming that would be in the same category. (They're just small right now)
They were grown from fruit from Stan's farm, so I'm hoping there may be a chance one or two of them could turn out to be some sort of hybrids. (Thought I think that's probably wishful thinking)

US 852 is probably the only hybrid that's fully hardy well into zone 7 (might possibly even be able to survive borderline 6b as long as it's not too far north).
Title: Re: F2 citrange winter hardiness trial
Post by: lavender87 on May 27, 2019, 04:13:43 PM
  All effort would be meaningless if we fail to accelerate the ripening time, so their fruits can be harvested before the first frost of winter arrival. Even in zone 8a where I live, people growing Thomasville citrangequat had problems with ripening time of the year. Some versions of citrangequat trees do offer good taste of fruits when fully riped. I know some stubborn folks would upset to hear about unknown hybrid of citrangequat because of their outdated knowledge that citrangequat is a genetic dead end. If someone have questions about whether or not citrangequat could have some zygotic seedling, they can contact Stan Mckenzie to ask about its seedlessness.

   The original Thomasville Citrangequat fruit was described as being seedy and very tart, with mainly trifoliate leaves and thorny, but some of Thomasville citrangequat tree from Stan offered nearly seedless fruits and some have mix foliate with very few trifoliate leaves, some trees even thornless, eventhough they were all come from Stan Mckenzie.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 27, 2019, 04:45:54 PM
Thomasville is flowering several times in my climate. Spring bloom is giving seeds when cross pollinated by other hybrids in the garden, while during the early July flowering there is usually no other citrus to pollinate it.
This gives seedless fruits. Thomasville seeds are giving only  nucellar seedlings, cross pollination is just necessary to induce  them.
Stamens of Thomasville flowers contain some fertile pollen grains, especially during hot weather. I managed to produce several dozens of its hybrids with 5star citrumelo.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 27, 2019, 05:57:01 PM
Ilya, when is 5* ripening in your location? Are your 5* X Thomasville seedlings vigorous?
Title: Re: F2 citrange winter hardiness trial
Post by: eyeckr on May 27, 2019, 10:57:04 PM
Amazing graft Kumin and good luck with all your trials.

Lavender87 you mention ripening of Thomasvilles. As long as they are sized up and juicy I've always used them like a lemon or lime substitute while they are green and they taste fine. Are you trying to get them to ripen until they are totally orange and eat them whole like a kumquat?
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 28, 2019, 03:12:54 AM
Ilya, when is 5* ripening in your location? Are your 5* X Thomasville seedlings vigorous?
Usually 5star starts to bloom at the end of April, fruits are yellow by November 10. But  if you keep them after  the harvest until January they are much less acid.

5starXThomasville seedlings are very variable, from the first batch of 20, only three are still alive after two years in the ground.
Last year pollination gave 40 zygotes, only three are as vigorous as nucellar 5stars

(https://a.radikal.ru/a30/1905/36/06752395b19a.jpg) (https://radikal.ru) 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 29, 2019, 02:16:34 PM
Ilya, I believe you have referred to 5*'s impressive storage life previously. What storage temperature has worked best for you? I haven't been very impressed by Poncirus storage duration in the past. It appears 5* is considerable better.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 29, 2019, 02:30:58 PM
I stored its fruits both in a basement with temperatures around +12C as well as at room temperature. Even in March they are mostly undamaged, juice is less sour and actually more abundant than just after a harvest in November, since the flesh is loosing its hardness.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:18:43 PM
Presently I am preparing Poncirus seedlings to be used as rootstock under segentrange scions. As soon as the larger seedlings begin new growth they have overcome transplanting shock sufficiently to use as rootstock. The smallest need to grow a good bit in size before use.

There are maybe 800 seedlings not potted at present. 300 + small ones are potted and 130 larger ones are potted of which about 12 have been grafted.

There's a lot of work to be done by autumn of this year.

300 plus recently potted Poncirus seedlings.
(https://i.postimg.cc/SnMf0WKb/IMG-20190607-131613.jpg) (https://postimg.cc/SnMf0WKb)


Several hundreds of this year's Poncirus seedlings - not potted. Sand used as weed control.
(https://i.postimg.cc/67xLBy72/IMG-20190607-131634.jpg) (https://postimg.cc/67xLBy72)

1-3 year old Poncirus seedlings. As they flush new growth, they should be ready to graft.
(https://i.postimg.cc/xc73FsnP/IMG-20190607-131702.jpg) (https://postimg.cc/xc73FsnP)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:39:00 PM
Poncirus contains several gene regions responsible for its freeze resistance and its genome is highly heterozygous. That is why  F1 hybrids with citrus are showing a large variation for winter hardiness.
Three hundreds of its F1 hybrids with very frost sensitive pummelo show a wide distribution of freeze damage.

 article (http://journal.ashspublications.org/content/128/4/508.full.pdf)

(https://b.radikal.ru/b13/1902/bb/5a2a6f76c8cf.jpg) (https://radikal.ru)

Quite possible that C35 citrange inherited a rather unfavorable set of gene alleles from its poncirus parent explaining its poor winter performance.

Ilya, considering that C-35 citrange may not include all of the genes providing cold hardiness found in Poncirus, I plan on not only sampling and testing within the segentrange progeny that have survived, but also crossing with the hardiest Poncirus hybrids approaching edibility that are available. I will be winter testing 5* Citrumelo and TaiTri this winter. If their hardiness approaches that of my survivors, they will be considered as parents.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:52:10 PM
The good and the bad:
This clone is the only one to show zero dieback after a low temperature reading of -11.8 deg. F in late January of 2019.
A defect of this clone is the failure to green up properly this spring. There is also overall low vigor. Regular foliar nutrient feeding has been started. This plant may not do well on it's own roots.

If it is possible to overcome it's defects, this plant may be used for breeding purposes, due to it's excellent cold hardiness.
(https://i.postimg.cc/gwqcnkDB/IMG-20190608-062358.jpg) (https://postimg.cc/gwqcnkDB)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 07:13:25 AM
A few current photos:

69 survivors selected for further evaluation - some have serious defects and may not be used for further breeding.
(https://i.postimg.cc/2VLxwHMW/69-Selected-Survivors.jpg) (https://postimg.cc/2VLxwHMW)

Conestoga # 011
One of the hardiest specimens - all but 1 twig removed as scions for grafting.
(https://i.postimg.cc/cKh7HPgp/011.jpg) (https://postimg.cc/cKh7HPgp)

2 Monofoliate survivors - appear rather Citrus - like. Conestoga # 058 and Conestoga # 064
 (https://i.postimg.cc/r0z4psL4/Monofoliate-June-14-2019.jpg) (https://postimg.cc/r0z4psL4)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 10:09:20 AM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 14, 2019, 12:30:03 PM
Does not look like albino chimera, probably either some root deficiency or a viral infection.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 02:48:24 PM
I tend to agree with you, Ilya. It lacks the layered look of chimeras. Several plants display yellow new growth that improves with foliar nutritional sprays. We have experienced a wet, chilly, prolonged spring to this point and there may be problems getting nutrients to the foliage.

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 05:06:05 PM
An example of defects: these two plants suffered bark freezing that healed and the plants recovered, but still are likely to carry the susceptibility.
Conestoga # 003
(https://i.postimg.cc/wRs0Zvgh/IMG-20190614-170042.jpg) (https://postimg.cc/wRs0Zvgh)

(https://i.postimg.cc/1g97XsrQ/IMG-20190614-170141.jpg) (https://postimg.cc/1g97XsrQ)
Title: Re: F2 citrange winter hardiness trial
Post by: Laaz on June 15, 2019, 07:43:51 AM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)

That's not variegation. Ilya is correct.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on June 19, 2019, 04:23:50 PM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)

Does anyone know what causes this?  It seems to be showing up on the new growth of Poncirus crosses. 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 19, 2019, 05:02:26 PM
I have additional plants with chlorotic growth. I haven't definitively determined the cause, hopefully it's nutritional rather than viral. In the worst cases apical growth is stunted and there is branching from a lower position on the stem.
(https://i.postimg.cc/06kcsdV7/yellow-1.jpg) (https://postimg.cc/06kcsdV7)

(https://i.postimg.cc/3yxC6rwB/yellow-2.jpg) (https://postimg.cc/3yxC6rwB)

Apical growth arrested, with unusual branching from a lower position.
(https://i.postimg.cc/2bqdkHhL/yellow-3.jpg) (https://postimg.cc/2bqdkHhL)

(https://i.postimg.cc/RN17ZJ6d/yellow-4.jpg) (https://postimg.cc/RN17ZJ6d)

(https://i.postimg.cc/FdJc5YXj/yellow-5.jpg) (https://postimg.cc/FdJc5YXj)

(https://i.postimg.cc/dL9CYMpS/yellow-6.jpg) (https://postimg.cc/dL9CYMpS)

(https://i.postimg.cc/HrZ7rwpw/yellow-7.jpg) (https://postimg.cc/HrZ7rwpw)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on June 19, 2019, 08:16:20 PM
It looks like just new growth.  I assume you have a nutrient plan for your trees.  The yellow should turn green as the growth matures.
Title: Re: F2 citrange winter hardiness trial
Post by: Delvi83 on June 28, 2019, 11:36:41 AM
Congratulation, it's a very good job !!!
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 23, 2019, 02:20:17 PM
Here are some photos from today showing the Segentrange survivors before being planted into the soil in preparation for winter. These will be slightly protected in mid-December to mid-March.

These are the hardiest survivors, many which are making good growth through the summer.
(https://i.postimg.cc/NyL7BCWc/Segentranges-July-23-2019.jpg) (https://postimg.cc/NyL7BCWc)


This plant is a monofoliate Segentrange sibling to the rest of the plants. The spines are very slender and rather long. Conestoga # 058
(https://i.postimg.cc/r07LQbLF/Monofoliate-Segentrange-July-23-2019.jpg) (https://postimg.cc/r07LQbLF)


# 010 Segentrange, one of the hardier, deciduous plants.
(https://i.postimg.cc/xkWs7Sq7/Segentrange-010-July-23-2019.jpg) (https://postimg.cc/xkWs7Sq7)


#002 Segentrange, an evergreen Segentrange showing good hardiness. This plant is not particularly thorny.
(https://i.postimg.cc/F7RB7GtT/Segentrange-002-July-23-2019.jpg) (https://postimg.cc/F7RB7GtT)


A TaiTri seedling making vigorous growth, having been planted from seed in late winter of 2019.
(https://i.postimg.cc/3y7jDJ43/Tai-Tri-July-23-2019.jpg) (https://postimg.cc/3y7jDJ43)


A Citrumelo also having been grown from seed in late winter of 2019.
(https://i.postimg.cc/XXFvtK1D/Citrumelo-July-23-2019.jpg) (https://postimg.cc/XXFvtK1D)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on July 24, 2019, 05:31:41 AM
I might have missed a post but do you have backups of the survivours? I just wonder if these survivours are already reliable hardy enough for slightly warmer climates than yours.
I have several seedlings here to test but my ground in the field is so bad that Poncirus shows literally no growth in years. Will be the same with hybrids.
So I need to do small scale tests here in my house garden with better ground.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 24, 2019, 07:43:41 AM
Mikkel, I don't have backups for all the survivors at this point. I have multiple backups for the best survivors. My intention is to have a lot of flowers blooming for open cross-pollination as well as controlled pollination. The protection I reference is planting in ground, but within a structure that can be covered and insulated against record low temperatures. I find that nutritional needs are met more naturally in open soil. However, I want to maintain some control over extreme temperatures and precipitation. I selected the best drained location on the property and will begin planting very shortly, so the roots can establish before winter.

The trees won't be protected until December so the cold will remain steady until spring. In the event that there's an unusually warm period in the winter, the heat must be vented outdoors. The intent is not to provide warmth during winter, rather to protect during sub-zero temperatures.

In regards to soil fertility, this region of Pennsylvania has soils that range from mediocre to very fertile, with the limestone soils being especially fertile. The greatest challenge on my property is drainage, rather than fertility, due to the clay content in the soil.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 27, 2019, 08:02:26 AM
January low temperatures had no impact on the fruitfulness of Poncirus. This tree is full of fruit as usual.
(https://i.postimg.cc/1fCf9RQN/Poncirus-fruits-Aug-26-2019.jpg) (https://postimg.cc/1fCf9RQN)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on August 27, 2019, 10:19:09 AM
January low temperatures had no impact on the fruitfulness of Poncirus. This tree is full of fruit as usual.
That's very encouraging. Do they fully ripen where you are?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 27, 2019, 10:43:43 AM
This is the same tree last year. The fruit ripens every year, but not before October.
(https://i.postimg.cc/njJc8tXs/IMG-20181005-072823.jpg) (https://postimg.cc/njJc8tXs)

(https://i.postimg.cc/JGP8Tk3B/IMG-20181005-072845.jpg) (https://postimg.cc/JGP8Tk3B)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 28, 2019, 07:28:00 PM
Many of the F2 Segentrange back ups have made good growth after being bark flap grafted onto Poncirus. These are smaller plants than the original survivors which have been field planted in preparation for winter. The plants are numbered and are labeled "Conestoga" a local river named for a Native American group that inhabited the area in the past. Early Swiss - German settlers subsequently carried the name to Ontario, Canada during the 1830's and named a river and town the same, albeit spelled the name slightly differently at times.

This scion made excellent growth in a short time.
(https://i.postimg.cc/V5ShWQwc/Scion-growth-Aug-28-2019.jpg) (https://postimg.cc/V5ShWQwc)


Conestoga #011 Deciduous
(https://i.postimg.cc/dhQmnrCT/Conestoga-011-b-Aug-28-2019.jpg) (https://postimg.cc/dhQmnrCT)


Conestoga #010 Deciduous
(https://i.postimg.cc/PpHmpDdx/Conestoga-010-Aug-28-2019.jpg) (https://postimg.cc/PpHmpDdx)


Conestoga #021
(https://i.postimg.cc/bSJSkHWz/Conestoga-021-Aug-28-2019.jpg) (https://postimg.cc/bSJSkHWz)


Conestoga #024
(https://i.postimg.cc/Q9NFZJXp/Conestoga-024-Aug-28-2019.jpg) (https://postimg.cc/Q9NFZJXp)


Conestoga #058 Monofoliate evergreen, this plant has pleasantly scented aromatic leaves when bruised.
(https://i.postimg.cc/ZWrn9Mn8/Conestoga-058-Aug-28-2019.jpg) (https://postimg.cc/ZWrn9Mn8)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 29, 2019, 03:38:35 AM
Nice looking plants.
Hope they will be able to harden before  frost.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 13, 2019, 02:48:15 PM
2 photos of  # 011 F2 hybrid top worked on mature Poncirus trees for the upcoming winter test. This selection is one of the hardiest and multiple clones have been propagated as backups. The 3rd photo is the original survivor of these clones.
(https://i.postimg.cc/zyV67Vs7/Sept-13-2019-Conestoga-011-top-grafted.jpg) (https://postimg.cc/zyV67Vs7)

(https://i.postimg.cc/nsqdS704/Sept-13-2019-Conestoga-011-b.jpg) (https://postimg.cc/nsqdS704)


This is the original plant on May 04, 2019. This plant is deciduous and hopefully can serve as a parent in further breeding.
(https://i.postimg.cc/hJn8jY1m/May-4-2019-a.jpg) (https://postimg.cc/hJn8jY1m)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 13, 2019, 06:32:07 AM
The oldest Poncirus tree I have. The origin was from Major C Collins in Tifton, GA a cold hardy Citrus enthusiast. This selection has larger fruit than average and slightly more juice and pulp. Seediness is not less. The fruit size difference is not dramatic, but noticeable.


(https://i.postimg.cc/kBv7gtzF/Poncirus-October-2019b.jpg) (https://postimg.cc/kBv7gtzF)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 15, 2019, 03:08:55 PM
Enclosed some actual Pictures of my Segendarin HRS899 (O or Q?) - it is surely different to poncirus - and also has some similarties - see photos enclosed. Some fruits show growths, which to my knowledge never occurs in Poncirus. The fruits also have a relatively long style and a small greenish tip, which I have observed does not occur in Poncirus fruits in this form. The smell of HRS899 fruits is a bit more pleasant than that of Poncirus fruits, and has a slight orange aroma. But look at the pictures that say more than 1000 words.

(https://i.postimg.cc/tnGkVjbx/DSC09203.jpg) (https://postimg.cc/tnGkVjbx)

(https://i.postimg.cc/8FVLHb32/DSC09208.jpg) (https://postimg.cc/8FVLHb32)

(https://i.postimg.cc/crgYGjNq/DSC09206.jpg) (https://postimg.cc/crgYGjNq)
Title: Re: F2 citrange winter hardiness trial
Post by: Bomand on October 15, 2019, 03:23:18 PM
A little diffrent from poncirus but one can see the similarities....hard to smell the picture.😁
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 15, 2019, 03:30:55 PM
I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or someone invents (finally) I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or somebody invents (finally) the transmission of smells and perhaps also of flavours - like of pictures, sounds, texts... I think he would get rich!
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 15, 2019, 03:38:41 PM
Great photos, do you have any photos of cut fruit? The fruit does look distinct from Poncirus. How does this tree's hardiness compare to Poncirus? I assume Poncirus has no hardiness issues in your location.

 I once transplanted a mature Poncirus tree with very pronounced nipples on the fruit. The stem end was also elongated a bit, giving a somewhat lemon-like appearance.  The tree trunk was 10 cm in diameter and did not survive transplantation. It would have been wiser to transplant a few of the small seedlings growing under the tree, or save some of the fruits.
Title: Re: F2 citrange winter hardiness trial
Post by: Bomand on October 15, 2019, 05:29:11 PM
I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or someone invents (finally) I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or somebody invents (finally) the transmission of smells and perhaps also of flavours - like of pictures, sounds, texts... I think he would get rich!  Yes I agree. Dont send me a fruit. I am too old to go to jail. I will just imagine😄.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 17, 2019, 03:35:29 AM
@Kumin:
 I cutted some years ago one and I remember they have some seeds and not much pulpe, which smelled like poncirus fruits, I did not taste them.l cut one or two after being dully ripe and droping down - I think in abut 4 weeks later. I will post phots than. Two fruits should contains seeds which are results of pollination with "Lemonade" - a sweet and very aromatic lemon like Citrus variety from New Zealand. I think the result of the hybridization will be a robust citrus hybrid with very aromatic fruits.

@Bomand:
;-)   But I don't think they'll put you in jail for a fruit. There was only once in human history a big problem because of a fruit..... that was back then in the Garden of Eden, also called Paradise!

Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 22, 2019, 02:58:22 PM
Please find my impressions and oictures from the first HRS899 seedling fruit I opened and tasted today in another thread here in the Forum:

http://tropicalfruitforum.com/index.php?topic=30863.msg369960#msg369960 (http://tropicalfruitforum.com/index.php?topic=30863.msg369960#msg369960)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 15, 2019, 12:16:13 PM
In preparation for winter, the open ground planted trees, as well as the potted trees have been enclosed in a cold frame shelter. This may not be needed in an average winter, but it provides a means for emergency protection if a 50 year Arctic cold event should occur. The very lowest temperature seen in this area in my lifetime was -24 deg F (-31.1 C) in January 1994. Such a temperature would wipe out all the pots and destroy all the other plants, at least to ground level.

This structure was hastily constructed as  we experienced a low temperature of 18 degrees (-7.77 C) earlier this week. The original plan was to cover in early December, but plans were changed due to weather forecasts. The plants easily coped with the 18 degrees. The plan is to protect the stems in order to  get flowering and fruiting in a few years.

There are no intentions of heating the structure, but in the event of temperatures lower than -10 deg F.(-23.3 C) it would be an option.

(https://i.postimg.cc/QH78F384/Nov-2019-cold-frame.jpg) (https://postimg.cc/QH78F384)

(https://i.postimg.cc/qN0Tg6Zq/Nov-2019-South-View.jpg) (https://postimg.cc/qN0Tg6Zq)

(https://i.postimg.cc/DWZRbrQv/Nov-2019-East-View.jpg) (https://postimg.cc/DWZRbrQv)

(https://i.postimg.cc/bSQ5j3PT/November-2019-West-View.jpg) (https://postimg.cc/bSQ5j3PT)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 15, 2019, 01:49:50 PM
With first frost coming two out of five of my cicitrumelo seedlings (5star citrumelo pollinated by FD) are preparing to shed its leaves.

(https://d.radikal.ru/d02/1911/ac/0dc31d028a5f.jpg) (https://radikal.ru)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 15, 2019, 02:00:15 PM
Ilya, early dropping of leaves is a good indicator of winter preparedness. My area had warm weather until recently leaving some plants unprepared. The hardiest plants from last winter appear to again be the best prepared at this point.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on November 18, 2019, 04:09:05 AM
Ilya, does your Citrumelo 5* drop leaves in late autumn? Mine keeps ist leaves over winter. Some of cause die but about 50% survive in a merely mild winter. Trifolis, which is said to be F2 and less hardy, changes colour and drops some leaves. Most hardy PT hybrids seem to drop leaves but also keeps some. Also leaves on my yuzu turn yellow and drop off. Not sure how many of them will get lost.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 18, 2019, 08:54:04 AM
Robert,
5 star is never dropping leaves here in the autumn. Some of them are dropped during the winter while still green. This happens during Arctic episodes with strong winds.
Interestingly, like you see in the cross above, this trait is recovered in 2 out of 5 back crossed seedlings.
One of them has leaves with  poncirus-like odor and taste , while those of another have only faint bitterness and smell like a true citrus.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on November 19, 2019, 03:48:47 AM
so there is one that drops leaves and might be of better quality?
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on November 19, 2019, 03:52:36 AM
(https://i.postimg.cc/PCWZj79n/852-1.jpg) (https://postimg.cc/PCWZj79n)
This is my 852 with fruits. Pictures taken last Saturday.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 20, 2019, 03:32:34 PM
Nice looking fruit. After they're ripe, new photos would be welcome 😁.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on November 21, 2019, 06:22:17 AM
They may look nice but they won't taste nice  ;)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on November 25, 2019, 12:01:05 PM
Kumin, How old were your plants when you planted them out? They seem to be very large for 1 year old plants?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 25, 2019, 12:15:40 PM
The seeds were planted April 12 2018. They were germinated in a heated bed. Subsequently the seedlings were field transplanted in early June of 2018. They were 9- 10 months old at the time of maximum exposure to the winter low temperatures.
Some of these plants were grafted onto Poncirus rootstock during the summer, which resulted in some larger plants, but some of the original plants have good size. The soil planted trees are the originals, the potted plants are potted Poncirus rootstock, or F2 back-up Segentranges grafted on Poncirus rootstock.
To answer your question more directly, these plants will be 2 years old in April, 2020.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 25, 2019, 12:54:59 PM
A number of seedlings and grafted specimens as they show leaves preparing to abscise for winter.

A seedling of either Meyer lemon, or Moro blood orange showing good tolerance to this point. No expectations of winter survival.
(https://i.postimg.cc/1n3w1CGY/Nov-25-2019-Meyer-or-Moro.jpg) (https://postimg.cc/1n3w1CGY)


Ichangquat 6-7-2 seedling showing shoot damage - not deciduous (not expected to be).
(https://i.postimg.cc/svqkBb17/Nov-25-2019-Ichangquat-6-7-2.jpg) (https://postimg.cc/svqkBb17)


TaiTri seedling not showing much damage, partially deciduous at this point.
(https://i.postimg.cc/JyN33HxM/Nov-25-2019-Tai-Tri.jpg) (https://postimg.cc/JyN33HxM)


5* Citrumelo showing minor tip damage, not deciduous at this point.
(https://i.postimg.cc/308HrGSR/Nov-25-2019-5-star-Citrumelo.jpg) (https://postimg.cc/308HrGSR)


Segentrange # 58 monofoliate, not deciduous, showing a bit of tip damage (off photo). Original plant (in soil).
(https://i.postimg.cc/75YbtGqq/Nov-25-2019-058.jpg) (https://postimg.cc/75YbtGqq)


Segentrange #21 deciduous, showing little damage. On Poncirus rootstock.
(https://i.postimg.cc/8FXyf6zc/Nov-25-2019-021.jpg) (https://postimg.cc/8FXyf6zc)


Segentrange #001 deciduous (not last year), no damage. On Poncirus rootstock.
(https://i.postimg.cc/CnskD3s7/Nov-25-2019-001.jpg) (https://postimg.cc/CnskD3s7)


Segentrange # 010 deciduous, no damage. On Poncirus rootstock.
(https://i.postimg.cc/hhvX07Pg/Nov-25-2019-010.jpg) (https://postimg.cc/hhvX07Pg)


Segentrange # 011 deciduous, no damage, possibly
the hardiest specimen. On Poncirus rootstock.
(https://i.postimg.cc/k2J3xWqv/Nov-25-2019-011.jpg) (https://postimg.cc/k2J3xWqv)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on December 18, 2019, 02:42:46 PM
Multiple layers of frost cover have been placed over the plants . Neither the white overwintering plastic, nor the frost cover have a dramatic effect used on their own. The exterior poly cover shields the interior from the wind allowing the frost cover to become more effective. Supposedly using the two in conjunction can have an 8-10 degree benefit. This is the first time I will be using either of them. In the event of unseasonably mild weather, I will remove the frost cover.

This protection may be a bit of pampering, but I'm eager to get to flowering and fruiting as quickly as possible.

(https://i.postimg.cc/R3phjtfx/Frost-Cover-17-Dec-2019.jpg) (https://postimg.cc/R3phjtfx)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 24, 2020, 08:23:55 AM
Our winter has been relatively mild to this point, with numerous lows at 15 to 17 degrees F. One of the segentranges has developed purplish leaf coloration. If I'm very lucky this may be inherited from the Ruby blood orange grandparent? A blood colored segentrange would be interesting, but certainly unproven at this point.
The coloration is clearly a response to cold temperatures, but there's no certainty that any fruit would develop similar coloration.


(https://i.postimg.cc/PNft3Q7D/Purple-segentrange.jpg) (https://postimg.cc/PNft3Q7D)
Title: Re: F2 citrange winter hardiness trial
Post by: Florian on January 24, 2020, 08:43:56 AM
Exciting nonetheless. Keep up the good work!
Title: Re: F2 citrange winter hardiness trial
Post by: tesilvers on January 24, 2020, 09:54:00 AM
Kumin, I love what you're doing. About ten years ago, I had planned to do the same (only not with C-35 specifically), but only got so far as to call the seed vendor. I was supposed to call back in a few months when it would be seed harvest time, but other things of life distracted me. In February, I plan to follow through this time and do a smaller scale version of your project. In the meantime though, I've been growing yearly batches of US 852 seedlings (thanks to Stan McKenzie) and most years all of the seedlings (nucellar and zygotic) have winterkilled. Occasionally a few have survived a winter, only to get killed in the next winter. Last winter only one seedling survived, so I recently dug it up and brought it indoors out of fear. I'm hoping to high graft a piece onto trifoliate later to see if it is reliably hardy here. We're zone 6b but just about on the border of 7a.

(https://i.postimg.cc/YG8cSbb6/US852-seedling.jpg) (https://postimg.cc/YG8cSbb6)

In all the years I've dabbled in container growing citrus and growing Poncirus in the ground, 2019 was the first time I'd ever tried a hand pollination. I used pollen from an old Poncirus (I think was Rubidoux) on 3 flowers of a potted calamondin. So far, I've got two definite hybrid seedlings.

Keep up the great work with your F2 C-35's!!!
Tom
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 24, 2020, 10:07:36 AM
tesilvers, interesting, in which county are you located? I'm only 40 miles north of Harford/Cecil counties.
If I were to repeat the winter trial, I would increase the number of seeds initially sown, but would pre-select the seedlings, field planting only vigorous, certain zygotic specimens.
Glad to hear from a colleague.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 24, 2020, 11:56:12 AM
I'm glad to hear reports on progress, and serious attempts to progress in winter hardiness in citrus.
 haven't put out any F2 plants this year.  Rather I plan to graft lots of F2 seedlings on Ponciris in spring, in hopes they will survive next winter.
And I plan to grow many F2 plants to fruiting, even if the part grafted and grown outside doesn't survive next winter.  I want to know how sugar, acid, and resin segregate.  And I want to learn to test for survival at various temperatures.
If some  segentranges were reliable in zone 7, some of their seedlings might give a much better percentage of zone 6 survivers.
Title: Re: F2 citrange winter hardiness trial
Post by: tesilvers on January 25, 2020, 06:09:39 AM
Hi Kumin,
We're in Washington county Maryland, near Harpers Ferry West Virginia. We hardly ever have any cold damage on Poncirus, but I haven't been able to keep any F1 types alive outdoors here.
I was a member of the Indoor Citrus and Rare Fruit Society back in the 80's, and my membership transferred to California Rare Fruit Growers afterwards, so I recognized Major Collins name when you mentioned him. The trifoliate I used on my potted calamondin is a descendant from the indoor citrus society seed bank offerings.
I'll keep your advice in mind when I order seed soon, but I have to operate within my Christmas money budget.   ;)
I hadn't mentioned it but I'm also trying to simultaneously improve trifoliate without citrus interbreeding. So far, I've got about a dozen zygotic seedlings of Flying Dragon lined out to see how much variation the fruit will show. I plan on extending that row as I germinate more seedlings. I've got another small batch germinating right now. Nucellar seedlings will become rootstocks; zygotic seedlings will get added to the row.
Thanks for inspiring the rest of us dreamers.
Tom
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2020, 06:52:47 AM
tesilvers, in the future I may have an improved flavor Poncirus, known as Poncirus+ selection available. This selection is supposedly zygotic and the fruits should have less resin and bitterness. My plants are juvenile seedlings at present, but should eventually produce large quantities of seeds. I have 7 of these young trees.

My F2 citranges approach Poncirus in cold hardiness, I don't know exactly how close at this point. The segentranges are 2 years old vs the Poncirus+ which are only 1 year old.
An option I have, would be to cross the Poncirus+ and the segentranges, hoping to combine almost all of Poncirus hardiness with reduced off flavors and perhaps some blood orange influence.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2020, 12:02:28 PM
tesilvers,
In the cold hardiness testing I've done over the years, there was greater variation of cold hardiness present in the F2 generation than found in the F1 generation. That being said, there was both increased and deceased hardiness in the F2 population.
While there were individuals with increased hardiness, they were few in number, approximately .5 %(vigorous).
Title: Re: F2 citrange winter hardiness trial
Post by: tesilvers on January 27, 2020, 07:52:07 PM
That would be reasonable to expect - to get a range of hardiness in the [true] F2. Were the approximately 0.5% with increased hardiness that you mentioned, out of the original 20,000 or out of the 15% zygotic F2?

Glad Poncirus+ is in the US. I was under the impression that it was only available in Europe. Less resin and bitterness sounds like a move in the right direction. Although, I haven't really noticed bitterness, just extreme sour (which is okay to me). But, the gumminess is definitely off putting.

I saw that you've been noticing differences in habit of dormancy. I had one Flying Dragon seedling that went dormant earlier than three siblings. I thought these four were all nucellar but maybe the one was actually a contorted zygotic seedling. My thought when I saw this one, was that it could give offspring with better (earlier and/or stronger) dormancy. Any thoughts on this matter from your experiences with the varied F2?
Thanks, Tom
(https://i.postimg.cc/21BPVKpW/also-back-in-november.jpg) (https://postimg.cc/21BPVKpW)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2020, 08:45:44 PM
tesilvers,
The .5 % is on the 15% zygotic seedlings. In zone 7 the percentage should be higher. It's a bit difficult to get solid numbers since there isn't necessarily a sharp cutoff between normal and dwarf plants, as there are also plants with intermediate vigor. There are a few cold hardy Citrus breeders with juvenile Poncirus+, but I'm unaware of any mature fruiting trees in the US. Flying Dragon is reported to have higher percentages of zygotic seedlings than some other Poncirus selections.

Clearly, one of your trees has a different coloration than the other 3. Even the remaining 3 might not all be nucellar seedlings. Careful observation might reveal subtle variation in foliage, thorns, flowering, and fruits.
Title: Re: F2 citrange winter hardiness trial
Post by: tesilvers on January 31, 2020, 03:34:04 PM
0.5% of the 15% zygotic - not an easy road by any means! :)
But I'm still gonna give it a go too. I just ordered 2 quarts of Sacaton which (contrary to early reports of being completely nucellar) has been reported to have 40-50% zygotic seedlings. I'm excited to finally get to try this out. Wish me luck!

I've never counted the numbers of "off-type" seedlings but I've definitely seen a relatively high percentage of obviously zygotic seedlings in Flying Dragon batches. I've got about a dozen straight-stemmed and straight-thorned ones planted in a row to evaluate for fruit variation whenever they mature. They came from an isolated mother tree, so I'm assuming they're from selfing which might explain their slow growth rate (- inbreeding depression maybe???). I'd like to try some intentional pollination this coming season using Rubidoux pollen on Flying Dragon to see if the percentage of off-type seedlings increases and to see if the vigor would be noticeably better.

Concerning the early dormant Flying Dragon seedling above... as a side project, I'd like to see how far North I can get a pure trifoliate to survive. Do you know of anyone growing trifoliate unprotected in zone 5b? I have a location in North Central Pennsylvania that I can test plant some seedlings and thought I might try the early dormant one there.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 31, 2020, 04:12:53 PM
The low percentage of survivors was mitigated by the initial 21,000 seeds, which should have produced 3,000 zygotic seedlings. .5 % of those gives approximately 15 (actually 12) healthy, vigorous survivors. This winter has been quite mild to this point and unless there's a dramatic change, the number of survivors would have been much higher. I was fortunate to have a severe winter, as it eliminated many less hardy plants.

I am satisfied that last winter's survivors were not a fluke, as the hardiest show no damage this winter.

I believe any Flying dragon seedlings not showing contorted branching should be zygotic, as nucellar seedlings should be all be contorted. Some of the contorted seedlings may also by zygotic.

Unfortunately, I am not aware of any more northerly Poncirus growers. However, although there has been dieback on mature trees on occasion, the last truly deadly winter was in 1994. I'm certain Poncirus can survive further north, but that dieback is likely increasingly severe as one goes north. I'm skeptical of survival in north-central Pennsylvania as well as central New York state. Coastal New Jersey/New York/New England may fare better.

If I'm successful in getting the segentranges to flower and fruit, I would expect a modest to high percentage of their zygotic seedlings to be hardy in zone 6b. I fervently wish I had embarked on this project sooner and more seriously.

Here a 2 photos of Conestoga # 11 segentrange top grafted on Poncirus out of doors. There's no damage on the # 11, but there's minor damage on late growing Poncirus twigs on the rootstock. These scions look very promising at present, but February and March are still remaining on the calendar.

(https://i.postimg.cc/8f1SBNvB/Feb-1-2020-Conestoga-11-outdoors-on-Poncirus.jpg) (https://postimg.cc/8f1SBNvB)

(https://i.postimg.cc/TL30rsw5/Feb-01-2020-Conestoga-11-d.jpg) (https://postimg.cc/TL30rsw5)
Title: Re: F2 citrange winter hardiness trial
Post by: tesilvers on February 03, 2020, 10:08:09 AM
Those grafts are looking good!

I agree about the Flying Dragon seedlings - all straight ones and some of the contorted ones should be zygotic. Speaking of which... here's one of the more vigorous obviously zygotic seedlings of Flying Dragon.
(https://i.postimg.cc/rzT4FGNV/IMG-4814.jpg) (https://postimg.cc/rzT4FGNV)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 02, 2020, 07:25:35 AM
Barring an unusual change in weather, there will be little to no cold damage this winter. Even the Meyer lemon seedling shows no real damage. Fortunately, the previous winter eliminated the tender seedlings. The protective structure was successful, but not really needed. The lowest temperature to this point has been +10 degrees F., not really zone 6b weather. This is 22 degrees F. warmer than last winter's low.

Meyer lemon unharmed, and unlikely to be harmed.
(https://i.postimg.cc/ns3Ftbc5/Mar-02-2020-Myer-seedling.jpg) (https://postimg.cc/ns3Ftbc5)

2 updated photos of Conestoga #11 scions grafted on Poncirus showing no damage.


(https://i.postimg.cc/hfRq6P1v/Mar-02-2020-Conestoga-11-b.jpg) (https://postimg.cc/hfRq6P1v)

(https://i.postimg.cc/Mnr3k9J5/Mar-02-2020-Conestoga-11.jpg) (https://postimg.cc/Mnr3k9J5)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on March 02, 2020, 11:57:57 AM
Barring an unusual change in weather, there will be little to no cold damage this winter. Even the Meyer lemon seedling shows no real damage. Fortunately, the previous winter eliminated the tender seedlings. The protective structure was successful, but not really needed. The lowest temperature to this point has been +10 degrees F., not really zone 6b weather. This is 22 degrees F. warmer than last winter's low.

Meyer lemon unharmed, and unlikely to be harmed.
(https://i.postimg.cc/ns3Ftbc5/Mar-02-2020-Myer-seedling.jpg) (https://postimg.cc/ns3Ftbc5)

Was the Meyer Lemon protected? 
Several of my seedlings that are hardier than Meyer have shown damage, and the low here was 20 F





[/quote]
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 02, 2020, 12:18:27 PM
The structure these trees are in is unheated. However, the combination of white overwintering poly plus the 3 layers of frost cloth likely provided 8-10 degrees of protection in addition to 100% shielding from wind. If this winter had been a repeat of last winter, I don't think the Meyer would have stood a chance at survival, let alone being undamaged. I have no plans for the Meyer, simply threw it inside on a lark. None of my plants suffered much damage either. The frost cloth sheets were frozen together, even this morning. There was also shallow frozen soil around the interior of the structure.

This is great in regards to getting closer to flowering/fruiting, but doesn't help in further defining hardiness. If we'd had these temperatures last winter, I believe there may have been thousands of survivors.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 27, 2020, 03:27:27 PM
An interesting phenomenon I noticed today: when the Poncirus+ as well as the citrange hybrids have a mixture of deciduous and evergreen twigs/branches, the deciduous twigs fairly consistently push buds before the leafed twigs do. It stands to reason that a leafed twig has less urgency to replace the previous season's foliage.

Poncirus+ exhibiting both deciduous and retained foliage branches.
(https://i.postimg.cc/FfvMBtPK/IMG-20200327-091902.jpg) (https://postimg.cc/FfvMBtPK)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on March 27, 2020, 10:32:47 PM
From looking at your soil in the picture, it looks like you have a tractor and a disk.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 27, 2020, 11:45:51 PM
Thanks millet, actually being under a stay-in- place Covid 19 order by the governor gave me an opportunity to get some physical exercise. The winter weeds needed to go before getting out of hand. So the tools used were a narrow trenching shovel and a hoe. Although I have often thought about having a tractor, I can't really justify owning one on a 1 acre property.
(https://i.postimg.cc/bGcmHFhR/IMG-20200327-125024.jpg) (https://postimg.cc/bGcmHFhR)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 29, 2020, 07:30:35 PM
The original growing beds used for the 2018/2019 winter trial were not maintained, nor monitored since May 2019. Today, I walked over the unkempt beds and saw a surprising number of plants that grew from low stem/root positions last summer and have survived this very mild winter with little damage. A few of the plants are nearly as large as  the plants I sheltered and pampered for a year. I plan on letting them undisturbed an additional year, then evaluate any that emerge undamaged from the upcoming winter. These plants have now survived 2 winters unprotected in zone 6b, although the past one was very mild.

The first photo shows a plant with minimal thorniness, especially in the top half of the stem.
(https://i.postimg.cc/Btgx9gf0/mar-29-2020-e-3.jpg) (https://postimg.cc/Btgx9gf0)

(https://i.postimg.cc/Q9Vr8mYy/mar-29-2020-b.jpg) (https://postimg.cc/Q9Vr8mYy)

(https://i.postimg.cc/1gjjHQMv/mar-29-2020-c.jpg) (https://postimg.cc/1gjjHQMv)

(https://i.postimg.cc/342Fv5q4/mar-29-2020-a.jpg) (https://postimg.cc/342Fv5q4)

(https://i.postimg.cc/gXGH8Bbg/mar-29-2020-d.jpg) (https://postimg.cc/gXGH8Bbg)

(https://i.postimg.cc/xXrHLFKL/mar-29-2020-f.jpg) (https://postimg.cc/xXrHLFKL)

(https://i.postimg.cc/WFDbWsVz/mar-29-2020-g.jpg) (https://postimg.cc/WFDbWsVz)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 30, 2020, 10:41:50 AM
those plants might be already hardy enough in zone 7.
probably yes but do you think they are zygotic seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2020, 12:21:35 PM
mikkel, some of these are zygotic. Photos #2, 3, and 5 are zygotic for certain. However, some shoots sprouted belatedly from underground roots.Some of these may be F1 C-35 seedlings despite my statements to the contrary last year. I'm sure no C-35 plants had surviving above ground stems. When I made my selections in the spring of 2019, I only selected plants with above ground living stems.

There are indeed likely plants within my collection that could survive zone 7. I have a nephew living 200 miles (321 kilometers) south of my location (still a bit north of member eyeckr) . After I graft additional clones of my selections, I plan on taking a number of plants to his location for zone 7b trial. Of course fruit qualities, or lack thereof, remain to be revealed.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on March 30, 2020, 05:17:17 PM
From so many seedlings there are some tetraploids.  I wonder how you can identify them.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2020, 06:53:52 PM
Having grown thousands of Poncirus seedlings, I saw stocky, thicker leafed plants I felt pretty certain were tetraploids. I really didn't observe any citranges that I felt were tetraploids, but with so great a range of unique segregating characteristics, it's difficult to discern.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on March 31, 2020, 03:37:12 PM
yes they have thicker leaves, here it's a image that might help. The percentage is very low, maybe one in 1000 but you have many seedlings, maybe you can find one.

(https://www.researchgate.net/profile/Mary_Rus_Martinez-Cuenca/publication/303510309/figure/fig7/AS:367161752211456@1464549591120/sual-symptoms-of-B-toxicity-in-leaves-from-the-6-month-old-2x-and-4x-CC-seedlings-grown.png)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2020, 04:48:16 PM
Thanks lebmung, I will keep an eye open for tetraploids as I survey the plants. Is your interest related to the production of triploids, or for a different reason?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2020, 05:13:27 PM
Delete
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2020, 05:15:26 PM
Here are pictures of potential tetraploids:


(https://i.postimg.cc/MMM83nZx/IMG-20180518-061024.jpg) (https://postimg.cc/MMM83nZx)

(https://i.postimg.cc/0r0kJJ4K/IMG-20180811-154800.jpg) (https://postimg.cc/0r0kJJ4K)

(https://i.postimg.cc/SXy9f0h7/IMG-20180811-153842.jpg) (https://postimg.cc/SXy9f0h7)
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on March 31, 2020, 07:55:56 PM
Thanks lebmung, I will keep an eye open for tetraploids as I survey the plants. Is your interest related to the production of triploids, or for a different reason?

Yes a triploid with a yuzu would be nice.

Some in those pictures have round leaves but lack the short petiole.
Look for plants with very short petiole and smaller, they don't grow so vigorous at the this stage.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 01, 2020, 03:32:11 AM
Small seeds  even in partially zygotic varieties are enriched in spontaneous triploids
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 01, 2020, 01:07:13 PM
Conestoga 011 came through winter unscathed. I haven't seen damage on any of the numerous grafted trees of this selection. This is possibly the hardiest specimen I have, with the exception of Poncirus. If only I could "fast forward" the next several years. Grafted on outdoor Poncirus.
(https://i.postimg.cc/phkcsr22/5-1-2020-Conestoga-11-overwintered-without-outdoors-damage.jpg) (https://postimg.cc/phkcsr22)

Conestoga 058 monofoliate selection, not as hardy as 011 and 010, but likely as hardy as TaiTri, or possible a bit hardier. Original plant in coldframe. Presently flushing.
(https://i.postimg.cc/LgzHhGLY/Conestoga-058-no-winter-damage-in-cold-frame.jpg) (https://postimg.cc/LgzHhGLY)

Conestoga 010, hardiness close to Conestoga 011. Hardier than TaiTri and 5* citrumelo. End of season high graft onto outdoor Poncirus.
(https://i.postimg.cc/tZhVhvHP/Conestoga-10-late-season-graft-on-Poncirus-no-winter-damage.jpg) (https://postimg.cc/tZhVhvHP)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 03, 2020, 06:33:51 AM
The monofoliate Conestoga #058 appears to appeal to both aphids and especially slugs. There seems to be a preference for this clone over the others. The leaf scent is more pleasant on this plant also. Hopefully this may be an indication of fruit flavors?
Small Conestoga 058 graftlings, one with signs of leaf feeding damage.
(https://i.postimg.cc/RqJt0GMj/IMG-20200503-061935.jpg) (https://postimg.cc/RqJt0GMj)

(https://i.postimg.cc/TykbK45X/IMG-20200503-061941.jpg) (https://postimg.cc/TykbK45X)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 03, 2020, 05:52:56 PM
To have a monofoliate cold hardy hybrid is an interesting progress
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 03, 2020, 06:09:25 PM
This clone is not the hardiest of the original survivors, but fairly close. During limited winter testing it compared favorably with TaiTri, perhaps a bit hardier. More extensive testing should help determine it's true hardiness.

#058 is likely the plant in the back, with #067 being the plant in the front.


#058 is one of these two monofoliate specimens. This photo was taken before numbers were assigned to the survivors. There is a short length of original seedling stem, but less than the several hardier selections.
(https://i.postimg.cc/t1VFkkq1/IMG-20190614-065158.jpg) (https://postimg.cc/t1VFkkq1)
Title: Re: F2 citrange winter hardiness trial
Post by: poncirsguy on May 03, 2020, 08:23:14 PM
How do you determine if an next generation is hardier.  If it is and you go 1 degree 2 cold then its dead and of no use.  Do you have a refrigerator/freezer that you can test 1 degree at a time for precision.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 03, 2020, 08:49:41 PM
I see cold damage as incremental. Best case: no discernable damage. Worst case: total failure as you indicated. Between the two extremes there should be a gradient from hardy to non-hardy. Poncirus at my location falls into such a gradient. Once past the first year seedling stage, almost never totally killed, usually unharmed, but occasionally damaged with subsequent regrowth and recovery. I would expect the hardiest selections to follow a similar, but lower scale.

In regards to testing, I would rely on natural, empirical conditions rather than relying on artificially produced testing. Firstly, I don't have such facilities, secondly, cold damage occurrs on a number of fronts, ranging from late Autumn freezes to absolute low temperature in midwinter, to duration of various levels of damaging cold, continuing to late dehydration caused by sun and wind during periods of frozen soil. Finally, Spring freezes can injure tender, new growth.


All of these conditions may be reproducible, but not within my capability. I suggest that selecting an exact point on the thermometer for making or breaking the test for hardiness doesn't weigh in on  the large number of variables.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 04, 2020, 02:59:11 AM
For me the main problem is very mild winters that we experience recently. I am overwhelmed with hybrid seedlings so this season decided to experience with artificial freezing. For the moment have some encouraging results of freezing two month old hardened seedlings at -8C for two hours, approximately 20% of them survive, some without any damage.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 04, 2020, 03:45:39 AM
Excellent point, Ilya. I'm probably overthinking this. The idea of cold testing seedlings at an early stage would certainly screen out excessive numbers of tender seedlings. I was thinking of testing chambers for large seedlings, which seems impractical in my situation.

However, pre-screening small seedlings would be a quick, contained process. A freezer with a thermostat and timer sounds easily doable. (The timer would be for me, so I don't get distracted)!

Most years we will have opposite challenges, in your case, eliminating marginal plants. In my case, not having the exposure so severe as to eliminate all seedlings.

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 11, 2020, 01:11:57 PM
The month of May is proving to be payback for the winter we escaped. Southeastern Pennsylvania hasn't been spared in the present Arctic cold wave. Saturday had light snow flurries during the afternoon.

I don't usually make much distinction between frosts and freezes. Subfreezing winds, however, can't be ignored. There was ice in unprotected shallow water and even a crust of frozen soil in freshly disturbed, exposed surfaces.

There is more Spring cold damage on Poncirus, than I have ever seen previously. The outdoor Conestoga # 011 damage paralelled that of Poncirus, but was not more severe.
(https://i.postimg.cc/m1gTz3Hg/IMG-20200511-090859.jpg) (https://postimg.cc/m1gTz3Hg)

(https://i.postimg.cc/HcLNb6BR/IMG-20200511-091006.jpg) (https://postimg.cc/HcLNb6BR)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on May 11, 2020, 03:03:40 PM
From what you wrote, it seems that the previous warm weather brought the trees out of dormancy, and then the cold snap was able to do the damage.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 11, 2020, 05:25:20 PM
Yes, they're in active growth as are many other trees. Peaches appear to be a total loss for the year. Strawberries at an 80% loss with two more nights of low temperatures, tonight and tomorrow night.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 11, 2020, 09:21:08 PM
Yes, they're in active growth as are many other trees. Peaches appear to be a total loss for the year.
Well, there is a reason peaches were considered a Southern crop and not something for Pennsylvania.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 14, 2020, 06:33:42 PM
Growth habits of several Poncirus/Poncirus hybrid seedlings:

Poncirus +: nothing remarkable noticed in plant habit
(https://i.postimg.cc/q6cg9JrW/May-14-2020-Poncirus-plus-a.jpg) (https://postimg.cc/q6cg9JrW)

5* Citrumelo: densely branched, strong tendency toward being  evergreen,  stocky plant, sturdy trunk develops early, height shorter for age

(https://i.postimg.cc/MnHKYbnC/May-14-2020-5-star-Citrumelo-a.jpg) (https://postimg.cc/MnHKYbnC)

(https://i.postimg.cc/DWbv9vd5/May-14-2020-5-star-Citrumelo-b.jpg) (https://postimg.cc/DWbv9vd5)

TaiTri: slender wispy branches, tendency for branches to droop over. vigorous, but not stocky

(https://i.postimg.cc/N5JH6xsX/May-14-2020-Tai-Tri-a.jpg) (https://postimg.cc/N5JH6xsX)

(https://i.postimg.cc/gx1L5k6k/May-14-2020-Tai-Tri-b.jpg) (https://postimg.cc/gx1L5k6k)


Conestoga plant awaiting a number, dense branching, a bit like TaiTri in growth habit
(https://i.postimg.cc/pyVrsn1J/May-14-2020-Conestoga-un-numbered.jpg) (https://postimg.cc/pyVrsn1J)


Conestoga 006 
(https://i.postimg.cc/vgZyt5H1/May-14-2020-Conestoga-006-a.jpg) (https://postimg.cc/vgZyt5H1)


Conestoga 058: monofoliate plant, the most Citrus-like in appearance, a bit less hardy, a few bifoliate leaves, slugs favor this clone. Very strongly evergreen.
(https://i.postimg.cc/MMFC04F4/May-14-2020-Conestoga-058-a.jpg) (https://postimg.cc/MMFC04F4)

Original 058 plant, good vigorous growth, upright growth habit.
(https://i.postimg.cc/06gV4GsH/IMG-20200514-072723.jpg) (https://postimg.cc/06gV4GsH)

Conestoga 010: deciduous, hardy plant, small  leaves.
(https://i.postimg.cc/TLL7xPt7/May-14-2020-Conestoga-010-a.jpg) (https://postimg.cc/TLL7xPt7)


Conestoga 011: deciduous, very hardy plant, strong, open branches. Twin thorns frequent, small-medium leaves with wavy edges.
(https://i.postimg.cc/nXF3z2dQ/May-14-2020-Conestoga-011-a.jpg) (https://postimg.cc/nXF3z2dQ)

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 17, 2020, 06:36:09 AM
400 of 800 Poncirus seedlings to be budded/grafted as soon as the caliper increases a bit. At this stem diameter any budding/grafting would take very steady hands and very good vision! Fortunately I'm near sighted, removing my glasses will put these right in my focal range.

The bark may be a bit too fragile to allow much manipulation, however. The buds/scions would also need to be of a similar tiny diameter.
(https://i.postimg.cc/XX2rWNYW/IMG-20200517-061528.jpg) (https://postimg.cc/XX2rWNYW)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 17, 2020, 11:13:58 AM
Around 500 seedlings to be grafted?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 17, 2020, 12:33:13 PM
There are more than 800 ready this summer and next summer. I will have a bit of a challenge to get them all completed. I hope to do serious outdoor trials of all the clones I presently have. I have a nephew located 320 kilometers (200 miles) south of my location in zone 7b. He's agreed to trial some of my grafted clones at his location.

 In addition, there are several hundred original seedlings that were neglected, but survived in the original field trial beds. These had little to no damage during the past mild winter. I've weeded these beds and will give these plants an additional winter trial to test their hardiness. Some of these are starting growth in the last few days, about 10-14 days later than Poncirus. They are a mixture of evergreen and deciduous plants. Finding these plants, some of which had no dieback was a pleasant surprise. The low temperature during the winter was +10 deg. F (-12.2 C).
(https://i.postimg.cc/cr3PX3T9/IMG-20200517-121716.jpg) (https://postimg.cc/cr3PX3T9)

(https://i.postimg.cc/NLcNBnx4/IMG-20200517-121802.jpg) (https://postimg.cc/NLcNBnx4)

(https://i.postimg.cc/k6tyqQ2L/IMG-20200517-121914.jpg) (https://postimg.cc/k6tyqQ2L)

(https://i.postimg.cc/rR4c1PKg/IMG-20200517-121431.jpg) (https://postimg.cc/rR4c1PKg)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on May 17, 2020, 02:12:30 PM
Quite some trialing.  Wishing you and all of your seedlings  the very best.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 17, 2020, 02:37:51 PM
I like your work!
+10F was the average low for my area some years ago. In the last winters it is around +21F (-6C).
These second survivors might be already hard enough for my climate.
How many survivors are there now in total?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 17, 2020, 03:52:10 PM
Mikkel, I don't have a count, I will probably wait until all of them leaf out. There may be some that will fail to do so. I think there should be a minimum of 100. In about 2 weeks I should have a better idea of the numbers. It is quite possible that many of them will fail in a severe winter in this area. That's the reason a test in zone 7b is being planned.
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on May 18, 2020, 03:44:53 AM
Growth habits of several Poncirus/Poncirus hybrid seedlings:

Conestoga 010: deciduous, hardy plant, small  leaves.
(https://i.postimg.cc/TLL7xPt7/May-14-2020-Conestoga-010-a.jpg) (https://postimg.cc/TLL7xPt7)


Conestoga 011: deciduous, very hardy plant, strong, open branches. Twin thorns frequent, small-medium leaves with wavy edges.
(https://i.postimg.cc/nXF3z2dQ/May-14-2020-Conestoga-011-a.jpg) (https://postimg.cc/nXF3z2dQ)

These two looks almost like pure poncirus to me, the leaf in the middle is shorter than usual F1 hybrid with trifoliate, the same cold hardiness as poncirus is another sign, that these are much more close to poncirus than orange...
Conestoga 011 reminds me one of my Tetraploid poncirus, shorter  petiole, wider leaves with wavy edges are one of the sign of tetraploid.

a| Tetraploid poncirus, b| regular diploid poncirus

(https://i.postimg.cc/KkZwbsV7/post-1-1190356891.jpg) (https://postimg.cc/KkZwbsV7)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 18, 2020, 01:23:35 PM
Jibro, since the F2 generation is genetically still quite close to the original parents, it stands to reason that the progeny most closely resembling either parent, will likewise have hardiness and fruiting characteristics similar to that particular parent. An honest assessment would likely conclude, that the most likely use and value of these plants is as parents, on the way to further refined and improved selections.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 19, 2020, 05:43:05 AM
Around 500 seedlings to be grafted?

Actually more than 800 (rootstocks, not scions). There will be multiples of the more promising scions.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 19, 2020, 11:36:54 AM
You will do it alone?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 19, 2020, 11:53:54 AM
Yes, I'm semi-retired and this is my only real interest. I've done many grafts and buddings since I was a teenager. So I'm actually looking forward to this. Some people gamble, some travel, some follow sports, I immerse myself in horticulture.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 26, 2020, 02:17:40 PM
 Two additional monofoliate plants.

Conestoga 064 rather large leafed, sparsely branched. There's an occasional bifoliate, or trifoliata leaf.
(https://i.postimg.cc/f3kxfCKT/26-May-2020-064-b.jpg) (https://postimg.cc/f3kxfCKT)

A different plant having slender, dense branches and small leaves. This plant was initially trifoliate.
(https://i.postimg.cc/0K1Dxsqb/26-May-2020-064.jpg) (https://postimg.cc/0K1Dxsqb)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 26, 2020, 02:41:19 PM
beautiful! I like the narrow leaved types the most. Interesting to see that you have exactly the same herbs around like I have in my garden half way round the world :)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 26, 2020, 04:34:33 PM
Yes mikkel, many, but not all of our weeds have European origins. The early settler's plants didn't arrive with phytosanitary certificates.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 30, 2020, 07:47:28 PM
Growth habits of several Poncirus/Poncirus hybrid seedlings:

Conestoga 010: deciduous, hardy plant, small  leaves.
(https://i.postimg.cc/TLL7xPt7/May-14-2020-Conestoga-010-a.jpg) (https://postimg.cc/TLL7xPt7)


Conestoga 011: deciduous, very hardy plant, strong, open branches. Twin thorns frequent, small-medium leaves with wavy edges.
(https://i.postimg.cc/nXF3z2dQ/May-14-2020-Conestoga-011-a.jpg) (https://postimg.cc/nXF3z2dQ)

These two looks almost like pure poncirus to me, the leaf in the middle is shorter than usual F1 hybrid with trifoliate, the same cold hardiness as poncirus is another sign, that these are much more close to poncirus than orange...
Conestoga 011 reminds me one of my Tetraploid poncirus, shorter  petiole, wider leaves with wavy edges are one of the sign of tetraploid.

a| Tetraploid poncirus, b| regular diploid poncirus

(https://i.postimg.cc/KkZwbsV7/post-1-1190356891.jpg) (https://postimg.cc/KkZwbsV7)

Jibro, I took a few minutes to examine Conestoga 011 in some detail and must agree that the petiole is shorter than the other plants. It appears to be only +/-  30% of the length of Poncirus petioles. I'm not certain this is a positive for my purposes, although if it's truly a tetraploid, I suppose triploids could be created at will. I will need to research how to get the ploidy tested at some point.
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on July 20, 2020, 05:23:37 AM
You can read about Tetraploid plant identification here: http://tropicalfruitforum.com/index.php?topic=24488.0 (http://tropicalfruitforum.com/index.php?topic=24488.0)

Chromosome counting can not be done easily without special fixings, stains and rather powerful microscopes.
The easiest "kitchen" methods for ploidy determination is comparative measuring of leaf stomata replicas
with the help of nail polish (colorless) and a microscope (x40 - x100 will do). You apply the nail polish on a clean dry leaf, wait for it to dry and the peel it off. Afterwards you mount the peeled nail polish on a slide and cover with glass slip.
I've been thinking about crossing Tetraploid poncirus with regullar poncirus, both with better taste and select triploid seedless more edible poncirus, but I am not sure if it's possible without in vitro technic Embryo rescue and how to idntify triploid one...
Your Conestoga 011 may be good seed parent for similar purpose...

I may have several tetraploid poncirus seedlings and two poncirus clones with better taste have also short, wide petiole: " Sladka" and "Poncirus Plus"

(https://i.postimg.cc/SJhXx4FT/Poncirus-Plus-leaf.jpg) (https://postimg.cc/SJhXx4FT)


(https://i.postimg.cc/RqNrJJ9q/Sladk-leaf.jpg) (https://postimg.cc/RqNrJJ9q)

"Sladka" also have very thick and bumpy rind, this should by another sign of tetraploid:


(https://i.postimg.cc/RJMLfHJh/post-1-1190359289.jpg) (https://postimg.cc/RJMLfHJh)

(https://i.postimg.cc/yk6z6px4/sladka-fruit-bumpy-rind.jpg) (https://postimg.cc/yk6z6px4)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 24, 2020, 05:37:11 PM
Very interesting post, jibro. Do you do Citrus breeding? If so, have you developed any selections?
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on July 24, 2020, 07:54:43 PM
I've been thinking about crossing Tetraploid poncirus with regullar poncirus, both with better taste and select triploid seedless more edible poncirus, but I am not sure if it's possible without in vitro technic Embryo rescue and how to idntify triploid one...
It's both easily possible to make a cross, and easy to identify the triploid by its fruits. Triploids will be relatively seedless (or at least obviously far fewer seeds, sometimes tiny shriveled up seeds).

(Of course, you will actually have to grow the seedling until it becomes big enough to fruit, to determine that)
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on July 25, 2020, 02:37:16 AM
(Of course, you will actually have to grow the seedling until it becomes big enough to fruit, to determine that)

And that is problem, even if I get only 10 fruits from crosspolination, it's about 300 seeds with no way to select hybrids from nucellar clones (if you cross poncirus x poncirus) until they start fruiting and it took 8-10 years in my zone 6....with high probability one extreme winter, which may kill even older poncirus.

Very interesting post, jibro. Do you do Citrus breeding? If so, have you developed any selections?

I have no "big plans" for citrus breedings, I just collected more edible poncirus clones and I want to test them all in the same conditions to determine if they really have better taste...

I may try some crosses with orange or mandarine varieties, because I am curious if these "more edible" poncirus clones can create F1 poncirus hybrids with better tasting fruits than existing citrumelo and citrange...
This year i tried pollinated my fruiting poncirus with Ponderosa pollen because I am curious if some of them may produce hybrids as mother and I also have one fruit from more edible FD pollinated with Citrumelo 5*.
My biggest "success" so far is one very dwarf Flying Dragon seedling from 2017, it had first 3 flowers this spring and it has more flower buds again, so it looks like I found another precocious clone...
(https://i.postimg.cc/JsN5ND13/Flying-Dragon-Red-Dwarf.jpg) (https://postimg.cc/JsN5ND13)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 25, 2020, 04:40:39 PM
 Current photos of recent outdoor high grafts on Poncirus, as well as grafts on 1 year Poncirus.

Photos of the interior of the cold frame housing 1 1/2 year old grafted clones of the original survivors & 2 1/2 year old original surviving seedlings.
(https://i.postimg.cc/7fjCnKYx/IMG-20200725-074955.jpg) (https://postimg.cc/7fjCnKYx)

(https://i.postimg.cc/fStz3hdY/IMG-20200725-074946.jpg) (https://postimg.cc/fStz3hdY)

Recent outdoor high grafts of TaiTri, 5* citrumelo, and various Conestoga selections.
(https://i.postimg.cc/dDycT6XR/IMG-20200725-075523.jpg) (https://postimg.cc/dDycT6XR)

A few of 440 recent grafts on Poncirus year old seedlings. There are 8 seedlings per pot.
(https://i.postimg.cc/G4pMvht0/IMG-20200725-075220.jpg) (https://postimg.cc/G4pMvht0)

Conestoga #001 high graft on Poncirus needs support due to very rapid slender growth.
(https://i.postimg.cc/3kWsYZgD/IMG-20200723-070548.jpg)[/url




More recent outdoor grafts on fruiting age Poncirus.
[url=https://postimg.cc/CzR7KrQY](https://i.postimg.cc/CzR7KrQY/IMG-20200723-065926.jpg) (https://postimg.cc/3kWsYZgD)

2nd year graft of Conestoga #011 on fruiting age Poncirus, hopefully it'll flower in 2-3 years.
(https://i.postimg.cc/JDwgMVqs/MVIMG-20200721-165040.jpg) (https://postimg.cc/JDwgMVqs)



Title: Re: F2 citrange winter hardiness trial
Post by: vnomonee on August 06, 2020, 02:12:10 PM
Quote
I have no "big plans" for citrus breedings, I just collected more edible poncirus clones and I want to test them all in the same conditions to determine if they really have better taste...

Are there any large scale citrus breeding programs using Poncirus+ (reduced/without bitterness) to recreate/improve all of the "bad tasting" hybrids that already exist?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 06, 2020, 03:15:31 PM
I'm not aware of many Poncirus+ trees in the US, especially in regards to mature, fruiting trees. This should not be a major obstacle, as well grown Poncirus fruits rather young. I've been in the process of grafting juvenile phase Poncirus+ on year old seedlings, I'm uncertain as to the success rate, but I should know shortly.

Answering your question a bit more directly, this would be a great project for someone with a collection of various zygotic cultivars, used as maternal, or paternal parents. Walt has suggested doing exactly what you're proposing.

I would love to see young people getting involved with cold hardy Citrus breeding. Realistically, some of us have collected, selected, or created selections that while not reaching all of the goals we're seeking, may provide valuable breeding material for further advances.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 16, 2020, 07:59:44 PM
This is Conestoga A-26 the tallest specimen at 28 months of age. Knowing it was at least 8' (2,43M) tall, I measured it and found it to be 108" (2,74M) tall. The node count is just over 100 nodes. Due to it's very rapid growth it will likely still be several years until flowering. This tree strongly resembles Poncirus, with leaves smaller than Poncirus. The growth is extremely upright. The cold frame is 11' (3.35M) tall and will probably be too low by next autumn.


(https://i.postimg.cc/ZCfdWcgk/Aug-16-2020-node-count.jpg) (https://postimg.cc/ZCfdWcgk)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 23, 2020, 01:39:02 PM
Top grafts on Poncirus after 15 months.
(https://i.postimg.cc/HrHwdfyj/00100lr-PORTRAIT-00100-BURST20200923132418104-COVER.jpg) (https://postimg.cc/HrHwdfyj)



(https://i.postimg.cc/WtNtpT9B/00100lr-PORTRAIT-00100-BURST20200923132347511-COVER.jpg) (https://postimg.cc/WtNtpT9B)

Top grafts on Poncirus after 2-3 months.
(https://i.postimg.cc/4YmBDCkt/IMG-20200923-132127.jpg) (https://postimg.cc/4YmBDCkt)

(https://i.postimg.cc/p9Py9vW5/IMG-20200923-132241.jpg) (https://postimg.cc/p9Py9vW5)

The 15 months old scions have gone through a mild Winter without damage. There are approximately 20 scions to be exposed during the upcoming winter.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on September 24, 2020, 01:40:18 PM
It is really impressive how fast they grow. Have you ever thought of using paclobutrazol to trigger flowering?
Ilya has done some research on this.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 24, 2020, 02:44:14 PM
Mikkel, our Summers on the East Coast are characterized by hot, humid weather with fairly long days. Your days are obviously longer during Summer. Our Summers can come to an abrupt end, which can leave tender, vulnerable growth  going into Winter. I have been pleasantly surprised by the growth rate of the Citrus in my project.
I've skimmed through methods to hasten flowering/fruiting, but feel that a bit more scaffolding development would be beneficial before utilizing those techniques.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 10, 2020, 12:32:52 PM
This may be rather optimistic, but several potential flower buds have developed on Conestoga 011 top grafts on Poncirus. These scions will only be 3 years old from seed by April 2021. They clearly appear different from the majority of the vegetative buds. Perhaps they are simply imperfect male flowers on the scion's first bloom.

If these are not flower buds, I suspect they are precursors to flowering in 1-2 years.

Vegetative bud.
(https://i.postimg.cc/QFkqQZWY/Vegetative-bud-b-10-10-2020.jpg) (https://postimg.cc/QFkqQZWY)

These could potentially be flower buds.
(https://i.postimg.cc/30vXWsTB/Flower-bud-a-10-10-2020.jpg) (https://postimg.cc/30vXWsTB)

(https://i.postimg.cc/Yvk6qDy6/Flower-bud-b-10-10-2020.jpg) (https://postimg.cc/Yvk6qDy6)

(https://i.postimg.cc/d7RtQnpy/Flower-bud-e-10-10-2020.jpg) (https://postimg.cc/d7RtQnpy)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on October 10, 2020, 02:41:36 PM
Last picture looks tetraploid.   :)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 10, 2020, 03:29:25 PM
The photos are all from the same clone including the first one. The potential tetraploidy has previously been suggested. If tetraploid, the larger buds may be caused by tetraploidy rather than flower initiation.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on October 13, 2020, 12:15:34 AM
I have some F1 citrus x poncirus hybrids, within each plant there are varying leaf shape and thickness.  Perhaps varying amounts of tetraploid cells may be present in different branches of the plants.   This is apparent only when poncirus is part of the cross.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 21, 2020, 01:55:06 PM
Recent photos:

5* citrumelo - very vigorous and 8 ft. (2.43 meters) tall - 18 months from seed

(https://i.postimg.cc/6TnpmSQ2/5-star-Citrumelo.jpg) (https://postimg.cc/6TnpmSQ2)

Original test plot - 100's of survivors 30 months from seed most are unlikely to survive above frozen soil in the upcoming Winter.

(https://i.postimg.cc/xN2nQfdk/2020-Survivors.jpg) (https://postimg.cc/xN2nQfdk)

Monofoliate Conestoga #058 30 months from seed.

(https://i.postimg.cc/TLqYpLFj/Conestoga-058.jpg) (https://postimg.cc/TLqYpLFj)

Conestoga # 002 deciduous - The original plant is 30 months old from seed, very low thorniness. This is a 16 month old  plant grafted on Poncirus.

(https://i.postimg.cc/mc7T51Lx/Conestoga-002.jpg) (https://postimg.cc/mc7T51Lx)

Conestoga A-026 deciduous 10' ( 3 meters) tall 30 months from seed.

(https://i.postimg.cc/hfhcq5D1/Conestoga-A-26.jpg) (https://postimg.cc/hfhcq5D1)

Various Conestoga seedlings 30 months from seed.

(https://i.postimg.cc/Th4BnYxn/various-Conestoga-row.jpg) (https://postimg.cc/Th4BnYxn)

Ichangequat 6-7-2 18 months from seed suffered freeze damage and Botrytis infection during the past Winter.

(https://i.postimg.cc/5HgRyfpY/Ichangequat-6-7-2.jpg) (https://postimg.cc/5HgRyfpY)

Poncirus + entering autumn color change 18 months from seed

(https://i.postimg.cc/nXZ2D6Xv/Poncitus.jpg) (https://postimg.cc/nXZ2D6Xv)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on October 22, 2020, 03:24:20 AM
You have excellent  growing conditions. :)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 10, 2020, 01:57:53 PM
Various degrees of deciduous behavior among Poncirus and hybrids:

Soil grown Poncirus seedlings. Leaves are turning yellow, but few have been dropped.
(https://i.postimg.cc/V5Mk52T6/Nov-10-2020-In-ground-Poncirus.jpg) (https://postimg.cc/V5Mk52T6)

Poncirus in containers has dropped more of it's leaves.
(https://i.postimg.cc/mtjRH4Sb/Nov-10-2020-Containerized-Poncirus.jpg) (https://postimg.cc/mtjRH4Sb)

Hybrids in cold frame, with varying degrees of color change: TaiTri and F2 segentranges.
(https://i.postimg.cc/rdxqzrnH/nov-10-2020-cold-frame-c.jpg) (https://postimg.cc/rdxqzrnH)

Tallest trees in the far left are Poncirus+ more distant tall trees on the left are 5* citrumelo. the remainder of the trees are F2 segentranges.
(https://i.postimg.cc/V5N2Vt9c/Nov-10-2020-cold-frame.jpg) (https://postimg.cc/V5N2Vt9c)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 01, 2021, 10:04:24 AM
An update on the status of the hybrids I have at present:
 The ranking in regards to cold hardiness is very consistent from year to year. It's likely the hardiest trees are genetically very close to Poncirus. Hopefully there will be some Citrus traits expressed at time of flowering/fruiting in a few years. I see little or no difference to this point, in regards to cold hardiness, between Conestoga # 010,#011, and Poncirus.

In addition to the hybrids I am also comparing Poncirus+ and Poncirus in regards to cold hardiness. To this point, I haven't noticed less hardiness in Poncirus+.

The low temperature to date has been +10 deg. F. (-12 deg. C)

The trees in the cold frame are exposed to the same low temperatures, but have higher daily highs on sunny days. The most noticeable difference is that there's no desiccation inside the cold frame, unlike the evergreen grafts exposed to the outdoors.

TaiTri outdoor graft on Poncirus, shows no deciduousness - however, TaiTri in cold frame has dropped +/- 25% of leaves.
(https://i.postimg.cc/hQsK1fNh/Jan-01-2021-Tai-Tri.jpg) (https://postimg.cc/hQsK1fNh)

5* Citrumelo shows no leaf drop outdoors, nor in cold frame. The twigs don't show too much damage, perhaps a bit of desiccation.
(https://i.postimg.cc/68kT3GKN/Jan-01-2021-5-Star-Citrumelo.jpg) (https://postimg.cc/68kT3GKN)

Conestoga 058 segentrange in poor condition, strongly evergreen, most Citrus-like of all my hybrids, also the least cold hardy

(https://i.postimg.cc/HVbhKqL4/Jan-01-2021-Conestoga-058.jpg) (https://postimg.cc/HVbhKqL4)

Conestoga 001 segentrange partially deciduous appears relatively cold hardy.
(https://i.postimg.cc/mzcdSqq9/Jan-01-2021-Conestoga-001.jpg) (https://postimg.cc/mzcdSqq9)

Conestoga 010 segentrange, fully deciduous and second hardiest specimen.
(https://i.postimg.cc/cvbk80kW/Jan-01-2021-Conestoga-010.jpg) (https://postimg.cc/cvbk80kW)

Conestoga 011 segenrange, fully deciduous, hardiest specimen of my hybrids.
(https://i.postimg.cc/5YwsGv49/Jan-01-2021-Conestoga-011.jpg) (https://postimg.cc/5YwsGv49)
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on January 01, 2021, 12:17:44 PM
Hello Kumin, wish you a very good and healthy 2021 and further very good progress and success in your ambitioned breeding program.
I always like to read your interesting reports and view your pics.Best regards Frank 👍
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 04, 2021, 03:38:58 AM
Kumin, I wonder if you kept some nucellar seedlings in cold frame  as a control? What is their resistance?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 04, 2021, 01:05:21 PM
Ilya, that's a very good question. In the Winter of 2018/2019 most of the seedlings were killed to the soil level. During the Summer of 2019 several hundred roots sprouted shoots that grew until the Winter of 2019/2020, which saw low temperatures of -12 C (+10 F). Some are clearly zygotic, others have considerable uniformity. The present Winter low temperature has again been -12 C (+10 F) . The trees that survived last Winter's low temperature didn't make new growth until June. These trees show little damage to this point.

The trees in the cold frame show both more damage, as well as less damage than the outdoor trees. The outdoor trees show more desiccation, the cold frame trees have hardened off less, allowing the stems to be more succulent.

In regards to your question concerning C-35 trees in the cold frame, there are 2 trees I believe to be C-35 hitchhikers on F2 roots by means of root grafting. They have larger diameter straight stems. I am attaching  photos of outdoor survivors with minimal damage as will as 1 of the likely C-35 trees in the cold frame.


Outdoor survivors -  original plot
(https://i.postimg.cc/XBZVyz0N/Original-trial-plot-2.jpg) (https://postimg.cc/XBZVyz0N)


Original trial plot
(https://i.postimg.cc/hJh3gW8G/Jan-4-2021-outdoor-survivor-a.jpg) (https://postimg.cc/hJh3gW8G)


Original plot
(https://i.postimg.cc/dZFBhzCr/Original-trial-plot-8.jpg) (https://postimg.cc/dZFBhzCr)


A very likely C-35 tree in the cold frame. These trees have thicker, straighter trunks than the F2 trees.
(https://i.postimg.cc/RJvDk3Xk/Jan-4-2021-C-35-cold-frame.jpg) (https://postimg.cc/RJvDk3Xk)

The question of C-35 cold hardiness has been raised several times. My results have been that C-35 has considerable cold hardiness provided it has an opportunity to develop cold resistance over a long period. I suspect that suddenly going from warm temperatures (allowing active growth),to cold temperatures, results in much less satisfactory results.
Title: Re: F2 citrange winter hardiness trial
Post by: poncirsguy on January 04, 2021, 01:19:17 PM
My C35 was outside in winter and took a lot of damage at 10F after over 2 months with no warm weather.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 05, 2021, 08:29:36 AM
Poncirusguy, although my suspected C-35 trees survived the past Winter as well as this Winter to this point, their growth was delayed in the Spring. The 2 trees in the cold frame are triple the size of the outdoor trees.
Additionally, severe cold would almost certainly kill them to soil level. We have had minimal frozen soil since 2019. Our area is capable of frost depth of 36". Not only would C-35 tops be doomed, the roots might also be.
My focus is on the hardier F2 trees, a few of which might servive subzero F. temperatures.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 09, 2021, 01:52:43 PM
Midwinter photos of cold frame hybrids and one outdoor hybrid:

A heavier caliper Citrange seedling, nearing 3 years of age.
(https://i.postimg.cc/8FDNvNPG/Feb-8-2021-a.jpg) (https://postimg.cc/8FDNvNPG)

One of the largest Citrange seedlings, nearing 3 years of age
(https://i.postimg.cc/sMjTGLd8/Feb-8-2021-c.jpg) (https://postimg.cc/sMjTGLd8)

Monofoliate Conestoga #58 grafted on Poncirus, 16 months post grafting.
(https://i.postimg.cc/SYLGJ6Zk/Feb-8-2021-d.jpg) (https://postimg.cc/SYLGJ6Zk)

5* Citrumelo seedling.
(https://i.postimg.cc/rz23FQs6/Feb-8-2021-f.jpg) (https://postimg.cc/rz23FQs6)

Grafted Conestoga F2 monofoliate Citrange, 16 months post grafting.
(https://i.postimg.cc/4mZ5j0dd/Feb-8-2021-g.jpg) (https://postimg.cc/4mZ5j0dd)

Vigorous 5* Citrumelo seedling.
(https://i.postimg.cc/1fHHSKnK/Feb-8-2021-h.jpg) (https://postimg.cc/1fHHSKnK)

Original Conestoga #058 tree, nearing 3 years of age. Most Citrus-like of all my seedlings, also the least hardy.
#058 has the longest spines of all my trees. They are quite slender, though, unlike the stout Poncirus spines.
(https://i.postimg.cc/ZBp8MPzp/Feb-8-2021-i.jpg) (https://postimg.cc/ZBp8MPzp)

Out of doors Conestoga # 001, not fully deciduous, slightly less hardy than Conestoga # 11 and #10. Hardier than 5* Citrumelo, or TaiTri. This tree is 10' tall.
(https://i.postimg.cc/t7Rd5xmZ/Feb-8-2021-k.jpg) (https://postimg.cc/t7Rd5xmZ)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 10, 2021, 04:17:19 AM
Kumin,
What were the lows inside this frame?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 10, 2021, 04:40:36 AM
Ilya, the lows are the same as outside. To this point the lows have been 10 F  (-12C). The cold frame gets at least 10-15C warmer than outside during sunny days. On cloudy, windy days there is less temperature rise.

The greatest benefit is wind protection and daytime amelioration of cold temperatures. A downside is that the stem tissues remain a bit more succulent, which in the case of severe cold temperatures could worsen bark destruction by freezing.
Title: Re: F2 citrange winter hardiness trial
Post by: Perplexed on February 10, 2021, 06:32:53 AM
Kumin, I noticed that with 5* the leaves are always curly/wavy. That's the same for me, mine also have the same leaf pattern.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 10, 2021, 08:02:03 AM
Perplexed, all my 5* seedlings show the same wavy pattern. How old are your trees? Are your trees also seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 12, 2021, 12:48:24 PM
   At this point I'm contemplating a focus on creating crosses between the hardiest F2 Citrange survivors from the 2018/2019 Winter cold hardy trials and Changsha X Poncirus hybrids such as 852 Citrandarin and closely related selections. This would bring additional Citrus genetics into the "bloodline" while compromising little in the way of hardiness.

   Several downsides to the F2 Citrange selections are:

1. Poncirus off-flavors tend to be more pronounced in Citranges than Citrandarins.

2. Sweet Orange parentage leans toward longer periods of juvenility than Mandarin parentage.

3. At this stage the F2 Citrange selections appear to approach Poncirus in hardiness, but are likely to retain off-flavors and perhaps poor coloring. The three characteristics in their favor are hardiness, deciduousness, and at least some Citrus genes.

Benefits of using Changsha X Poncirus parentage in crosses.

1. Changsha Mandarins are more cold hardy than Sweet Oranges.

2. Adding Citrange X Citrandarin parentage should promote a more diverse genetic base.

3. Changsha Mandarins are highly colored, sweet, prolific fruit and seed bearers.

4. Changsha seediness is of little concern at this stage and is actually desirable for efficient seed production.

5. Using zygotic seed parents would streamline efficiencies by not wasting resources on nucellar seedlings.

6. If these breeding plans succeed, I hope to do new severe, cold hardiness test trials.





Title: Re: F2 citrange winter hardiness trial
Post by: Perplexed on February 12, 2021, 02:48:47 PM
Perplexed, all my 5* seedlings show the same wavy pattern. How old are your trees? Are your trees also seedlings?
Mine are about a year old in a pot. Still very young but is very cold hardy.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on February 12, 2021, 04:48:45 PM
   At this point...

just ideas:
It would be interesting to backcross it to the orange parent,  maybe as a side project beside your plans.
You could take HRS899A into your consideration too. It is an F2 Changsha x P.t. hybrid quite hardy and has good fruits as far as I heard about.
Title: Re: F2 citrange winter hardiness trial
Post by: Till on February 13, 2021, 01:45:29 AM
The curvy leaves of Swingle 5 Star are probably a sign of dehydration because roots could not provide enough water. My Sanford Curafora and US199 have also curvy leaves during winter and thereafter. It has nothing to do with frostbite as such leaves remain vital for a very long time.
Title: Re: F2 citrange winter hardiness trial
Post by: Till on February 13, 2021, 01:50:55 AM
Kumin, I am looking forward how your plans succeed. I would also try to cross your hardy seedling with Poncirus hybrids. When you have the potential for mass selection then use it. Crossing with citrus would compromize hardiness too much I think. But edible Changsha hybrids, as Mikkel suggest, seems to be reasonable, too, although I fear that would also weaken hardiness. Depends on how many generations you plan. At your growing conditions, 3 generations seem to be reasonable.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 13, 2021, 06:26:42 AM
Till, I presently have no plans of crossing back to pure Citrus due to loss of hardiness and number of years required to recover the required hardiness. The paths I'm interested in are crossing to edible Citrandarins, allowing the selections to self-pollinate, and crossing with Poncirus+ to maintain the greatest hardiness.
Additionally, the sooner the zygotic/nucellar status can be determined among the F2 selections, the better.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on February 13, 2021, 08:16:10 AM
I don't think backcrossing would lead to lower winter hardiness in every case, certainly in most cases, but in exceptions there might be a chance. Hardiness is not only controlled by one gene, but backcrossing could also work with several genes. It just has lower chances... but it has higher chances of sorting out the right genes than mixing them with other sources.... at least in theory...
In practice I would go both directions...

Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 13, 2021, 09:05:44 AM
This is a matter of numbers.
From my experience if you are able to raise ~200  zygotes from a backcross of F1 plant , there is at least a dozen that are as hardy as an original F1.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 13, 2021, 09:59:23 AM
The curvy leaves of Swingle 5 Star are probably a sign of dehydration because roots could not provide enough water. My Sanford Curafora and US199 have also curvy leaves during winter and thereafter. It has nothing to do with frostbite as such leaves remain vital for a very long time.

The curving leaves on 5* are most likely genetic in origin, as this characteristic is especially prominent is vigorous upright growth, even during Summertime. I haven't seen it relating to stress, as I'm able to distinguish 5* seedlings from all the other trees by this characteristic.

Ilya may be able to weigh in on his experiences with 5* leaf characteristics.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 13, 2021, 10:17:19 AM
In a summer they are only slightly curvy, while as of today , after  a night at -9.5C they are almost tubular.
I guess this is a sign of cold hardiness adaptation connected with  ability to diminish the surface of water loss.Grapefruit and orange leaves  are not showing this and stay flat until the lethal damage.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 26, 2021, 02:21:37 PM
 Feb 26 2021 branch condition comparison between TaiTri citradia, 5* citrumelo, and Conestoga 011 citrange.

TaiTri shows the most damage, with pitting of the bark surface. Unexpectedly, it hasn't shed its leaves. Not certain if this graft will survive the Winter at this point.
(https://i.postimg.cc/hfp35Y0D/Feb-26-2021-Tai-Tri.jpg) (https://postimg.cc/hfp35Y0D)

5* citrumelo leaves are mostly dead, however the bark surface appears to be in better condition than TaiTri and may be viable. Less bark surface pitting on this Citrumelo.
(https://i.postimg.cc/DJkCG37g/Feb-26-2021-5-star-citrumelo.jpg) (https://postimg.cc/DJkCG37g)

Conestoga 011 F2 citrange has good color and shows no ill effects from the Winter to this point. This tree is fully deciduous.
(https://i.postimg.cc/8sby7Y9R/Feb-26-2021-Conestoga-011.jpg) (https://postimg.cc/8sby7Y9R)


This Winter has been mild, with a few lows of 10 degrees F (-12 deg C). It has not been a serious cold test and forecasts don't indicate any in the remaining Winter.

After a night of rain the appearances are quite different.
 
This is an unidentified F2 citrange, with hardiness equal to, or slightly greater than 5* citrumelo.
(https://i.postimg.cc/JtgdNBxK/27-Feb-unidentified-F2-citrange.jpg) (https://postimg.cc/JtgdNBxK)

5* citrumelo after a night of rain. The appearance is much better.
(https://i.postimg.cc/Vrt02pyJ/5-star-Citrumelo-27-Feb-2021.jpg) (https://postimg.cc/Vrt02pyJ)


TaiTri on Feb 27 after a night of rain. The stem is a bit better looking than it was yesterday.
(https://i.postimg.cc/D8wLwCLM/Tai-Tri-27-Feb-2021.jpg) (https://postimg.cc/D8wLwCLM)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 27, 2021, 02:39:59 PM
5star is exceptionally resistant to the bark damage.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 27, 2021, 03:54:02 PM
Ilya, I'm surprised to see portions of the leaves still alive at this point. Have you encountered any deciduous 5* progeny in your breeding efforts? 5* does quite well for not being deciduous, but a deciduous version might be even better.

I'm surprised the outdoor TiaTri isn't dropping it's leaves, but the cold frame trees are partially dropping theirs.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 28, 2021, 03:54:32 AM
Do not have much experience with its open pollinated seedlings, but in crosses occasionally there are  some deciduous plants.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 11, 2021, 06:23:33 PM
Due to having 2 consecutive mild Winters there are still surviving plants in the original test plot. There's a newly discovered 3 year old deciduous seedling among less hardy plants. This seedling shows no cold damage, after a mild, but long Winter. I really should take a closer look at the remaining plants to determine if there are more surprises.

(https://i.postimg.cc/BjkX3GJc/2021-March-11-discovery-B.jpg) (https://postimg.cc/BjkX3GJc)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 28, 2021, 03:48:02 PM
Recent warm weather is driving some bud swelling on Poncirus, as well as some of the hybrids. Lows of 26 and 29 deg.F are predicted by end of week. Should not be a major problem, but is a bit of a concern after highs near 80 deg.F last week.

2 horizontal TaiTri twigs, appear to survive, a bit less resistant than 5* Citrumelo. Have dropped their leaves recently.
(https://i.postimg.cc/t195bDRJ/Tai-Tri-28-Mar-2021.jpg) (https://postimg.cc/t195bDRJ)


5* Citrumelo (Light green stems)has dropped all leaves and shows little Winter stem damage
(https://i.postimg.cc/tsJWpgL0/5-Star-Mar-28-2021.jpg) (https://postimg.cc/tsJWpgL0)

Poncirus+ twigs show no Winter damage.
(https://i.postimg.cc/dLLV0Tt9/Poncirus-plus.jpg) (https://postimg.cc/dLLV0Tt9)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 08, 2021, 06:09:01 PM
Conestoga 001 high grafted on Poncirus has wintered well and has bud break within 2" (5 CM) of the apical tip. This selection is not the very hardiest, but is likely about the 6th hardiest. It ranks hardier than TaiTri and 5* Citrumelo.

The tip of this graft is nearly 10'  (3.3 meters approximately) high from the ground.

This shoot made rapid growth last Summer and continued to do so into Autumn.
(https://i.postimg.cc/vxmw8Q0z/PXL-20210408-194918224.jpg) (https://postimg.cc/vxmw8Q0z)


Conestoga 001 after the initial Winter hardy trial.
(https://i.postimg.cc/gw051Y2q/IMG-20190607-131933.jpg) (https://postimg.cc/gw051Y2q)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 25, 2021, 10:01:19 AM
TaiTri post Winter recovery.
(https://i.postimg.cc/0Ksx4Hgt/PXL-20210517-221537165.jpg) (https://postimg.cc/0Ksx4Hgt)

segentrange # 011 showed no Winter damage.
(https://i.postimg.cc/XBphQfq2/PXL-20210524-204734315-MP.jpg) (https://postimg.cc/XBphQfq2)

Segentrange #058 graft, barely survived Winter, most Citrus-like in appearance.
(https://i.postimg.cc/ykN9pfV6/PXL-20210524-204906027.jpg) (https://postimg.cc/ykN9pfV6)


An additional #011 Segentrange, no Winter damage.
(https://i.postimg.cc/N5rG0TD7/PXL-20210524-204706465.jpg) (https://postimg.cc/N5rG0TD7)

Segentrange showing poor Winter hardiness.
(https://i.postimg.cc/WhVYDc6W/PXL-20210524-204753442.jpg) (https://postimg.cc/WhVYDc6W)

Outdoor 5* Citrumelo showing complete recovery after Winter.
(https://i.postimg.cc/LhJgzJvh/PXL-20210524-204919337.jpg) (https://postimg.cc/LhJgzJvh)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 25, 2021, 10:17:37 AM
Have Taitri and 5star shown the same degree of recovery this season?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 25, 2021, 10:31:04 AM
Yes, Ilya, their hardiness in my location was nearly identical. The surprise for me was that the TaiTri out of doors showed no deciduous behavior. The trees in the unheated cold frame were partially deciduous. 5* showed no deciduous behavior until new Spring growth flushed out of doors. The cold frame 5* still retain last year's foliage.

TaiTri and 5* are more hardy than my most tender Segentranges and less hardy than the hardiest segentranges.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 25, 2021, 05:38:52 PM
For me TaiTri seedlings were more hardy than some 5Star seedlings this winter. Both were under a snow cover.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on May 26, 2021, 05:51:21 AM

TaiTri and 5* are more hardy than the most tender Segentranges and less hardy than the hardiest segentranges.
[/quote]

Kumin, what are the hardiest Segentranges?

Of my garden-citri Ichangensis IVIA from seed, Citrumelo 5*, Citsuma Prague and Citrandarin US812 (from seed) are about equal in hardiness. Yuzu3 survived the last winter without any dieback or even loss of foliage. Citrange Morton (on Swingle Citrumelo) and some yuzu from Bernhard Voss died. Most likely my fault caused by wrong protection which allowed the winter sun to heat up the shelter and broke dormancy. Morton was not well established and Swingle might not be the right rootstock. Tmin was -10 to -12. Not really low in fact.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 26, 2021, 08:29:21 AM
Zitrusgaertner, the segentranges I refer to are the selections that survived the Winter cold hardy trial in 2018/2019. Out of ~20 000 seedlings several dozen survived in varied condition. I subsequently named the more remarkable selections "Conestoga" series and assigned individual numbers to them.

Conestoga 011 and 010 are the very hardiest, with about 8 more close in cold hardiness. Several of the most Citrus-like phenotypes were also kept and propagated, these are less hardy than 5* and TaiTri. Conestoga #010 and #011 approach Poncirus in hardiness.

None of the selections are mature enough to fruit. The hardiest selections have a rather Poncirus like appearance and may also exhibit similar off flavors.

Coldest temperature during trial, January 2019
(https://i.postimg.cc/1Vfjz9pY/IMG-20190131-071759.jpg) (https://postimg.cc/1Vfjz9pY)


~20 000 seedlings April 2018
(https://i.postimg.cc/2LRZ1GvR/IMG-20180515-080403.jpg) (https://postimg.cc/2LRZ1GvR)


Segentrange survivor among many dead seedlings.
(https://i.postimg.cc/KRtd386d/IMG-20190409-124615.jpg) (https://postimg.cc/KRtd386d)

3 year old survivor in the original trial row, never protected.
(https://i.postimg.cc/hJmC6yKN/PXL-20210409-143333111.jpg) (https://postimg.cc/hJmC6yKN)
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on May 27, 2021, 10:09:46 AM
Very interesting. Did you apply any sun protection? My opinion is, that more citri are killed by sun than by frost alone. They are all on own roots by now, are they? Du you plan to craft some on PT?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 27, 2021, 10:32:16 AM
Zitrusgaertner, there was no sun protection provided, per se. However, the planting density certainly provided some shading. The original survivors remain on their own roots, but I've grafted several hundred clones of the originals. Some are grafted on fruiting age Poncirus, others are on young Poncirus seedlings. So, the majority are indeed grafted on Poncirus.

Presently I'm in the long wait until they begin flowering/fruiting. At that point it should become apparent if any are edible, or if they're essentially glorified near-Poncirus relatives.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 28, 2021, 04:06:53 AM
Fingers crossed that there are already some plants with edible fruit! Just from theory. I would guess that a backcross with Citrus is is a good option with these F2 survivors.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 28, 2021, 09:05:38 AM
Mikkel, being quite close to the original hybrid, selecting for extreme cold hardiness likely selected survivors with predominantly Poncirus genetics. However, unless sterile, they're possibly good candidates, as parents in further crosses.

My present goal is to cross the hardiest selections with Citrandarins. Further selections among that progeny should present more opportunities to find the highly sought after "Hardly edible" results. I'm encouraged by the number of breeders involved in this quest.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 29, 2021, 04:49:19 PM
Like always,  one gardener but a hundred planners :) Sorry for being one of those planners...

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 29, 2021, 05:47:44 PM
Mikkel, the reason I'm reluctant to use pure Citrus is twofold: I'm eventually going run out of years, so I'm limited in the number of generations I can grow to fruiting. The other reason is that I need nearly all of the Poncirus hardiness to reliably expect survival in my plant hardiness zone.

For persons not needing such an extreme level of hardiness, my plan is probably overkill. Hopefully, eventually there will be variously cultivars tailored to specific regions. I doubt there will be a "one size fits all" cultivar.

There are different approaches taken by breeders, none of which is necessarily wrong. An example would be regions requiring early fruit ripening to avoid fruit freezing in the Autumn before fully ripening.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 29, 2021, 06:29:51 PM
I thought if you already have a F2 (your C35 seedlings) with almost the hardiness of Poncirus, it would be a good idea to cross it with the original Citrus parent of C35. As you have an almost hardy hybrid, but with still inedible fruits, you have already achieved 1 goal. A backcross with Citrus could bring the focus to edible fruits.
If a plant had edible fruits it would make sense to cross it with Poncirus or with C35.
According to the ideal backcrossing scheme
A x B -> F1 
F1 x F1 -> F2S1
F2S1 x A / B -> F3BC1
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on May 29, 2021, 06:50:16 PM
btw have you read about grafting on Limonia spec. (not C.limonia but Limonia the genus)? It's just something I read, but they say that grafts on Limonia flower very soon after grafting, almost immediately. But I am not sure if this also happens with immature grafts.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 29, 2021, 08:04:12 PM
mikkel, are you referring to grafting onto https://citrusvariety.ucr.edu/citrus/limonia.html ? It appears to induce precocity, but might be very frost sensitive, requiring greenhouse protection. If it consistently promotes precocity it may be worth the expense.

I understand your reasoning behind the suggestion of Conestoga segentranges as parents with Citrus. If a parent with near Poncirus hardiness, but containing a percentage of Citrus genetics were used as the hardy parent, the progeny should have additional Citrus genes, while retaining a good measure of cold hardiness. This may be feasible in a warmer zone, but would likely fail here due to our cold plant hardiness zone. The resulting cross would likely be a bit less hardy than C-35 citrange. However, this approach may well be advantageous in a warmer zone.

I calculate that the hardiness on the hardiest Conestoga selections would benefit from a potential slight hardiness boost by having a hardy segentrandarin (F2) as a breeding partner. If there's no gain in hardiness, perhaps any loss in hardiness could be kept to a minimum.

So the bottom line for me is a reluctance to lose any of the hardiness in the Conestoga selections, as it's all needed to survive in my zone 6b.

 
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on June 01, 2021, 04:58:24 PM
Mikkel, the reason I'm reluctant to use pure Citrus is twofold: I'm eventually going run out of years, so I'm limited in the number of generations I can grow to fruiting. The other reason is that I need nearly all of the Poncirus hardiness to reliably expect survival in my plant hardiness zone.

For persons not needing such an extreme level of hardiness, my plan is probably overkill. Hopefully, eventually there will be variously cultivars tailored to specific regions. I doubt there will be a "one size fits all" cultivar.

There are different approaches taken by breeders, none of which is necessarily wrong. An example would be regions requiring early fruit ripening to avoid fruit freezing in the Autumn before fully ripening.


I'm not going to be using backcrosses to citrus for my work either, with two exceptions. 

1. Kishu Seedless has a dominant gene for seedless.  Its pollen is good so 1/2 of its progeny should be seedless.  And Kishu is very sweet.  Ponciris could use more sweet.
2. C. medica is reported to be very precocious.  Its hybrid with P+ might be worth making to get more precocity.  That could mean more generations in my lifetime.  I'd like that.  It also is said to have very large fruit.

That said, I'd be open to making crosses back to citrus if someone in zone 7 or 8 wanted to grow out a bunch of 3/4 citrus seedlings.  No hurry though.  I won't have bloom for a while.  Years.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 01, 2021, 05:31:02 PM
Do you see a technical advantage in "wild" crossing? Or is it just your choice?
I do both or better I will do backcrossing in the future :) . But I see more advantages (apart from the long waiting time) in backcrossing, because it is probably easier to plan.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 01, 2021, 05:48:27 PM
Mikkel, does wild crossing refer to "open pollination", vs controlled pollination? If enough of the breeding stock flowers in a few years, controlled pollinations may become overwhelming, at which point a portion of the crosses may well be open pollinations.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 01, 2021, 06:56:46 PM
I use "wild crossing" only in the absence of a good English term for the opposite method of species-restricted crossings as practised in backcrossing. I don't prefer one over the other, I just feel that it is more predictable what to expect from these backcrossings (as you stay within the given genpool). I am interested in any strategy and the reasoning behind it.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 01, 2021, 08:34:46 PM
Mikkel, perhaps you are referring to outcrossing vs backcrossing within the original parents (sweet orange and Poncirus). Backcrossing should narrow the results more than outcrossing would.
The main reason I want to use the segentranges is that they've gone through a very vigorous screening for cold hardiness. The reason I want to use segentrandarins as breeding partners is potential shorter generational cycles, cold hardiness, lower off flavors, and potential earlier ripening of fruit.

In hindsight I suspect US 852 would have been a good seed source. There are a number of tri-specific cold hardy hybrids. These appear to be vigorous in many cases (Thomasville).
Title: Re: F2 citrange winter hardiness trial
Post by: hornad on June 02, 2021, 12:19:26 AM
Has anyone crossed Poncirus+ and Changsha yet?
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on June 02, 2021, 03:50:00 AM
Has anyone crossed Poncirus+ and Changsha yet?

Has anybody used PT+ for any new cross yet? There are a lot of interesting things that could be tried. PT+ X Grapefruit Enzo for example. Enzo has a remarkable hardiness and its fruits are quite frostresistant aswell.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 02, 2021, 06:10:38 AM
I'm aware of a number of persons in the US that have Poncirus+, but not certain any are mature enough to flower/fruit. I have trees that are likely to flower in 2-3 years. Walt suggests many of the the original Poncirus hybrids should be remade with Poncirus+. The likelihood of hybrids existing in Europe should be better.
2 year old, 2 meters tall Poncirus+.
(https://i.postimg.cc/z3qLfV67/PXL-20210602-103043756.jpg) (https://postimg.cc/z3qLfV67)
Title: Re: F2 citrange winter hardiness trial
Post by: poncirsguy on June 02, 2021, 09:33:05 AM
What is the cold tolerance of poncirus plus.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 02, 2021, 10:43:52 AM
The lowest temperature mine have encountered to this point has been +10 F (-12C) so not a real challenge. There was no damage. Ilya and other European members may have a better answer for the absolute lowest temperature resistance.
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on June 02, 2021, 11:07:05 AM
there is no hard and fast cold temperature tolerance for poncirus plus.  It all depends on how slow the winters temperatures cool down, was there a hot spell right before the freeze, how healthy the tree is, how strong the wind, and on and on.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 02, 2021, 12:42:46 PM
I have not seen any winter damage of poncirus for the last 30 years in the Paris region, but winter lows never exceeded -18C (0F). But I know that in Kislovodsk, Russia one plant survived without protection several  nights with -28C (-18F) covered only by snow. It was lost later probably due to the neglect.
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on June 02, 2021, 02:56:37 PM
I had a Flying Dragon planted close to the south wall of a metal barn. The first real cold spell it was killed. A member of the forum wrote that if I had planted the tree on the north side of the barn, it would have properly hardened off before the real cold weather arrived, and survived.  I am located at 5,240 ft above sea level in zone 5..
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 03, 2021, 05:11:51 AM
Mikkel, perhaps you are referring to outcrossing vs backcrossing within the original parents (sweet orange and Poncirus). Backcrossing should narrow the results more than outcrossing would.
The main reason I want to use the segentranges is that they've gone through a very vigorous screening for cold hardiness. The reason I want to use segentrandarins as breeding partners is potential shorter generational cycles, cold hardiness, lower off flavors, and potential earlier ripening of fruit.

In hindsight I suspect US 852 would have been a good seed source. There are a number of tri-specific cold hardy hybrids. These appear to be vigorous in many cases (Thomasville).


                           
I was thinking more of the dichotomy of hybridisations between different citrus species (species hopping), such as Pt x Orange ---> F1 x mandarin --->F2 x pomelo ---> F3 x kumquat ---> and so on
in contrast to backcrossing, where the hybridisations are limited to one parental species.

In theory, I imagine a crossing plan as follows:

F1 cross C35 (Pt x orange)

x selfing

---> F2
mass selection (like you did with the C35 seedlings)

backcross of the hardiest with Citrus

---> F3 
then: mass selection for desired traits

backcross to the same crossing partner like in F2

and so on.

Apart from the time it takes...

I would guess that by concentrating on a few traits and limiting it to one backcross partner, the variance of the offspring can be better limited within the desired traits.

The hybridisation of new Citrus species is also promising, but has the disadvantage that the number of seedlings must be larger, because the combination possibilities are simply more divers and there may be undesirable gene combinations that lead to completely different traits than in the parent species. Ilya once gave an example of sweetness, which is encoded by different genes in 2 citrus species, but the combination of both leads to sour hybrids (I hope I remember the example correctly).

Both has its reason and depends on what is to be achieved. I will do both as there are so many other factors that are involved (e.g. no flowers on a certain plant and the year is lost and so on)
but for a designed breeding program I would prefer a backcrossing scheme.

Wild hybridisation is good to find new types and new combinations.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 03, 2021, 10:41:25 AM
Many different schemes will work if a very large  hybrid population be used, but for this one needs a fertile zygotic parent.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on June 03, 2021, 11:20:18 AM
Mikkel.  I recently got 5* for crossing with the zygotic citandarins I got last year.  My plans are to citandarin x 5* as well as citandarin x citandarin.  Of course which crosses I make will depend on what blooms.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 03, 2021, 04:27:25 PM
@Walt, yes plans are plans and only what flowers flowers... that's the hard truth :)
I found many zygotic seedlings among the 5Star and N1tri seedlings I got as a from @Ilya. Even some monofoliate ones among the 5Stars.
These are good varieties for breeding.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 03, 2021, 05:20:48 PM
Here's a photo of a few Bishop citrandarin seedlings. Although one report indicated that the seedlings were nucellar, I see enough variation to indicate some zygotic seedlings.
Bishop citrandarin is a double flowered seedling of US 852. I found the fruit to be edible, or more accurately drinkable when diluted. The flavor is acid, yet sweet, rather intense with just a fleeting hint of Poncirus, the opposite of an aftertaste. The flavor is reminiscent of kumquat/mandarin and this is the lingering flavor, rather than Poncirus. The tree is reported to be hardy to 6 degrees F.
(https://i.postimg.cc/gXnMwxhg/PXL-20210528-181954061.jpg) (https://postimg.cc/gXnMwxhg)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 03, 2021, 05:36:44 PM
@kumin What is Bishop Citrandarin? is it from Alan Bishop?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 03, 2021, 05:50:41 PM
Indeed, I believe eyeckr did the honors of naming the selection. The past Saturday I grafted 25 scions onto Poncirus rootstock, hopefully a number of them will succeed. As I wait for my trees to mature I'm selecting a group of potential pollen/seed partners.

https://www.youtube.com/watch?v=FCyvolXNHCs (https://www.youtube.com/watch?v=FCyvolXNHCs)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on June 03, 2021, 06:45:14 PM
Thanks for the link!
Nice to see that his research has fruited.
I did a bypass graft with 5Star on a Poncirus rootstock this spring the first flush is already as twice as strong as in the last years I will try that on other plants it might give immature plants also a push.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on June 04, 2021, 11:36:25 AM
Mikkel, this plant is a happy accident and is not a result of a breeding program.  Bishop Citrandarin was bought as US852.  However because it took years to fruit it is obviously a seedling.  When a small rooted cutting of US852 that I just got bears fruit it should be clearly evident if it is a zygotic plant or not by making a comparison.  Many flowers are double, which is probably not typical of US852.
Relatives enjoy the fruit, which led me to send it to eyeckr and kumin for evaluation.   
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 31, 2021, 07:46:03 PM
96 newly planted F2 citranges on Poncirus rootstock. Only the hardiest selections were included in this planting, as this is the lowest and coldest part of the property. I'm hoping for one more mild Winter until the trees get established.
(https://i.postimg.cc/xXS4FFKD/PXL-20210731-133628660.jpg) (https://postimg.cc/xXS4FFKD)

(https://i.postimg.cc/KRTWfy3D/PXL-20210731-133749723.jpg) (https://postimg.cc/KRTWfy3D)

(https://i.postimg.cc/xqh7Ld8d/PXL-20210731-185315759.jpg) (https://postimg.cc/xqh7Ld8d)
Title: Re: F2 citrange winter hardiness trial
Post by: Till on August 23, 2021, 04:07:12 PM
Cool. You are very hard-working. Nice that you have the space.
I have the space too but my climate is at the border of what Poncirus can tolerate. Summer are too cool and weather in spring unpredictable. I also like to see that people use their resources to improve hardy citrus. Very good.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 24, 2021, 12:51:27 PM
Till, I suspect the low temperatures in my area to be a bit colder than your area. In January, 1994 the lowest local temperatures were -31C for two consecutive mornings. These temperatures were lethal to any young Poncirus branches above the snow. More recently, a low of -25 C did moderate damage to late season Poncirus growth.

Our summers are hot and humid, but not on par with the Southeastern US, as our's are of shorter duration.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on August 24, 2021, 03:25:45 PM
the main problem here in Germany is the summers. in my area, a little further north than Till, it's even worse. Poncirus just doesn't like our summers and there is only moderate growth every year. The main sprouting is in July/August, but these branches often don't survive the winter.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 27, 2021, 07:38:52 PM
Following several suggestions that segentrange Conestoga # 011 may be tetraploid, a sample has been submitted to a laboratory for ploidy testing. The results should be available in 10 days. Since this tree is the hardiest of the trial survivors, it may prove to be of use in producing seedless triploids when crossed to diploids.
(https://i.postimg.cc/NKHnM3dN/PXL-20201010-153315955.jpg) (https://postimg.cc/NKHnM3dN)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on August 27, 2021, 10:33:03 PM
Kumin, the leaves on your tree certainly have higher ploidy features.  I'll be watching this post to read what the testing shows.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on September 01, 2021, 09:56:10 AM
how can you recognise polyploidy? In Passiflora 4n varieties often have serrated leaf margins, like these poncirus leaves here.
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on September 01, 2021, 10:00:11 AM
From instances such as the over thickness of the leaves
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 02, 2021, 08:49:26 AM
The lab results are back and confirm that Conestoga #011 is indeed a tetraploid. I'll need to take this into consideration going forward.
(https://i.postimg.cc/VJJvGDn0/Report-0.jpg) (https://postimg.cc/VJJvGDn0)

(https://i.postimg.cc/8FW5Dcy1/Report-1.jpg) (https://postimg.cc/8FW5Dcy1)

(https://i.postimg.cc/bZ4JKk9C/Report-2.jpg) (https://postimg.cc/bZ4JKk9C)

(https://i.postimg.cc/V0sLjRz6/Report-3.jpg) (https://postimg.cc/V0sLjRz6)

(https://i.postimg.cc/r0kppTb5/Report-4.jpg) (https://postimg.cc/r0kppTb5)

(https://i.postimg.cc/JG24kZvr/Report-5.jpg) (https://postimg.cc/JG24kZvr)

(https://i.postimg.cc/JtKhR9QB/Report-6.jpg) (https://postimg.cc/JtKhR9QB)

(https://i.postimg.cc/rzqmX85k/Report-7.jpg) (https://postimg.cc/rzqmX85k)

(https://i.postimg.cc/mzygzqfJ/Report-8.jpg) (https://postimg.cc/mzygzqfJ)

(https://i.postimg.cc/GH2mtqMg/Report-9.jpg) (https://postimg.cc/GH2mtqMg)
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on September 02, 2021, 12:02:11 PM
Congrats, it's good to have confirmation that these different leaves are indeed a sign of tetraploidy.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on September 02, 2021, 02:10:52 PM
This changes your options.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 27, 2021, 07:36:16 PM
Tetraploidy as well as triploidy may enhance stress tolerance, including cold tolerance in Citrus. This may partially explain the hardiness of both Conestoga # 010 and Conestoga # 011. At this point I suspect that both are tetraploids.

An additional observation has been the twin thorns frequently present on # 011. I'm curious if tetraploidy causes, or contributes to that phenomenon?

https://www.frontiersin.org/articles/10.3389/fpls.2020.00330/full (https://www.frontiersin.org/articles/10.3389/fpls.2020.00330/full)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 25, 2021, 01:41:46 PM
A group of surviving outdoor F2 Citranges. These have been exposed to 2 Winters with lows of +10F degrees. I really won't know their hardiness until we get a colder Winter. These aren't the very hardiest trees. These trees have not been uprooted since the original planting.
<br />(https://i.ibb.co/qD5Kh4q/PXL-20211025-155430515.jpg) (https://ibb.co/qD5Kh4q)<br />

Outdoor planting of F2 Citranges, all grafted on Poncirus. Hoping for a mild Winter!
<br />(https://i.ibb.co/hYBh71x/PXL-20211025-170653154.jpg) (https://ibb.co/hYBh71x)<br />

Original Citrange trees surviving the past 2 Winters without any protection. There's a planting of American persimmons in the background. The persimmons were grown from seed and have been bearing fruit several years.
<br />(https://i.ibb.co/yVTFGnX/PXL-20211025-170724331.jpg) (https://ibb.co/yVTFGnX)<br />

Trunk diameter approaches 1" (2.5 cm) at ground level on this Citrange.
<br />(https://i.ibb.co/R2YM1YS/PXL-20211025-170836943.jpg) (https://ibb.co/R2YM1YS)<br />

Three F2 Citranges growing beside each other. The center tree favors Poncirus rather strongly. Each tree has different leaves.
<br />(https://i.ibb.co/dM4p6fH/PXL-20211025-171000870.jpg) (https://ibb.co/dM4p6fH)<br />
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on October 26, 2021, 09:22:27 AM
This is really good work! Thank you for sharing your experience with us!
 Are the plants in the first picture the ones that froze to the ground in the 1st winter and then sprouted again?
If those are already hardy to 10F, they are probably already hardy enough for many parts of Europe. The -11F survivors probably can't be topped for citrus hybrids at the moment. That's a big step forward!
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on October 26, 2021, 09:30:40 AM
Nice plants with very strong growth over summer. 
A striking demonstration how different are the climates for same zone at East Coast and in the Western Europe.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 26, 2021, 09:58:51 AM
Ilya, by observing the latitude of Europe, it's obvious that the Gulf Stream strongly moderates Western Europe's temperatures, but Western Europe lacks some of solar energy available to the Eastern US. Unfortunately for us, being on the eastern edge of the North American continent means we get cold Winters as well as fairly hot Summers. Areas south of my location aren't necessarily much hotter in Summer than my area, but the heat is of considerable longer duration. Our area can grow tobacco, melons, aubergines, sweet potatoes, and other heat loving crops. Marginal crops are okra, peanuts (groundnuts).  Cotton is impractical to grow in this area, but is found about 250 miles (400 kilometers) to our south.

I'm somewhat optimistic that some of my selections and additional items I've collected will survive and perhaps thrive in my area. The 5* citrumelo struggles a bit getting through Winter, but recovers strongly. Ichangequats have done poorly during Winter. TaiTri is quite similar to 5* in hardiness to this point. I'm not yet certain that Poncirus+ is equally hardy to regular Poncirus, as the last 2 winters have been mild.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 26, 2021, 10:14:27 AM
This is really good work! Thank you for sharing your experience with us!
 Are the plants in the first picture the ones that froze to the ground in the 1st winter and then sprouted again?
If those are already hardy to 10F, they are probably already hardy enough for many parts of Europe. The -11F survivors probably can't be topped for citrus hybrids at the moment. That's a big step forward!

Mikkel, all photos except the second are of survivors that sprouted at ground level during the Spring following the severe Winter test. As these seedlings were only 9 months of age when subjected to the cold test, they may possibly be hardier by now. However, the selections that were transplanted out of the test rows are the hardiest, with the possible exception of the 2 that are monofoliate/bifoliate.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 27, 2021, 06:35:51 PM
Pentafoliate leaf found on Conestoga # 001 Segentrange. This is the first seen to this point, perhaps there are additional ones. It's not hard to visualize ancestral Citrus having additional leaflets.
There appears to be a twin thorn at this node.
(https://i.postimg.cc/CRZ3rf38/PXL-20211027-222236891.jpg) (https://postimg.cc/CRZ3rf38)


Appears to have been seen previously on Poncirus hybrids. https://citrusvariety.ucr.edu/citrus/citrumelo_3821.html
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 05, 2021, 07:11:54 PM
Conestoga # 067 showing a bit of leaf color change, as well as minor deciduousness.
(https://i.postimg.cc/wtNBrYZJ/PXL-20211105-184029637-MP.jpg) (https://postimg.cc/wtNBrYZJ)
Conestoga # 058 also going through a leaf color change, including a branch color breaking to red leaves. No idea if the Ruby Blood Orange ancestry plays a role in this particular coloration. This clone has the thinnest, longest spines of all my trees.
(https://i.postimg.cc/qhd7VZHF/PXL-20211105-184000966-MP.jpg) (https://postimg.cc/qhd7VZHF)

Segentrange # 014 has rather citrandarin-like foliage. I haven't focused equally on all selections, as I've tended to focus mostly on a few of the more distinctive plants.

(https://i.postimg.cc/75Ljypkt/PXL-20211107-182544681.jpg) (https://postimg.cc/75Ljypkt)

 Segentrange # 002 has few thorns and those tend to be small. Pleasant to work with, in "sharp" contrast to the majority of the selections. Grafts of this clone haven't had as good "takes" as the other selections.
(https://i.postimg.cc/d7bfr3Tg/PXL-20211107-182152582.jpg) (https://postimg.cc/d7bfr3Tg)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 08, 2021, 02:49:26 PM
I got a bit of shock today as I was watering my seedlings in the cold frame. I happened to look up at the roof plastic film and did a double take. One of the  31 month old 5* citrumelo seedlings has 4 fruit in the upper branches. I consider this to be quite precocious. The tree is a bit over 9' (3m) tall. The tree likely flowered a bit late as the fruit aren't ripe at this time. So I suppose it's a precocious citrumelo! This tree was germinated from seed in April 2019

Thanks Ilya, this tree originated from seed you provided.

(https://i.postimg.cc/PP8gT0cK/5-star-citrumelo-first-fruit.jpg) (https://postimg.cc/PP8gT0cK)
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on November 08, 2021, 11:54:17 PM
This are very interessting positive news, fruits after 3 years from seeding !!!  Could there have been genes of precautious poncirus in this seeds ?
All what I ever heard is that in our colder climates blossoms and fruits of citrus seedlings need at least 5 to 8 years if its early ?
So this is a very encouraging case - congratulation Kumin  :D.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 09, 2021, 12:52:31 AM
I obviously don't know if the seed parent tree was self pollinated. My assumption is that it was. In all the thousands of Citrus, Poncirus and hybrid seedlings I've grown, I'd never seen any fruit this quickly. Due to the long juvenile period observed in grapefruit, this came as quite a surprise.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on November 09, 2021, 01:29:36 AM
I'm in zone 8a in the US, at a similar latitude to you (well maybe just a little bit less far north than Mhlacker).
I have multiple varieties that have been in the ground for 3 years and none of them have fruited yet. Well, only two (the Sudachi and Keraji) of them have seemed to begin to form just the tiniest beginnings of little fruits, but they never ripened in time and eventually fell off.
Of course something hardier like citrange might behave a little different. My Dunstan citrumelo has a reached a fairly medium size and still no appearance of fruits. But grapefruits are known to take much longer until they begin producing fruit.

Due to your more continental location, the summers where you are do just get a little bit warmer than where I am. About only 2 degrees F (just a little bit more than 1 degree C) but that can make a difference. Maybe your plants put on more growth during the growing season.

See, I'm growing in the Pacific Northwest region, and while hardy citrus may easily be able to survive through the level of cold there, they just have trouble putting on much growth through the year, due to short duration of the summers and the cool temperatures throughout most of the year, it seems to me.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 09, 2021, 03:53:24 AM
I got a bit of shock today as I was watering my seedlings in the cold frame. I happened to look up at the roof plastic film and did a double take. One of the  31 month old 5* citrumelo seedlings has 4 fruit in the upper branches. I consider this to be quite precocious. The tree is a bit over 9 (3 M )feet tall. The tree likely flowered a bit late as the fruit aren't ripe at this time. So I suppose it's a precocious citrumelo! This tree was germinated from seed in April 2019

Thanks Ilya, this tree originated from seed you provided.

Congratulations, 3m growth in two years is quite an achievement.
This probably explains the precocious fruits.
In my climate 5star seedlings  usually start flowering at this height, but it is reached only in 5-6 years.
Since these fruits are still green, they probably come from the late flowering in summer.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 11, 2021, 11:15:21 AM
I'm questioning whether having the apical leader strike the ceiling and deflect has any bearing on the early fruiting of 5 star citrumelo?

(https://i.postimg.cc/9wf7qGQh/5-star-ceilng.jpg) (https://postimg.cc/9wf7qGQh)

Additional plants approaching the ceiling, which will not be clipped back.
(https://i.postimg.cc/3kPrX2nT/East-wall-coldframe.jpg) (https://postimg.cc/3kPrX2nT)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 11, 2021, 11:53:32 AM
It really depends on the variety.
With hybrids of 5star I systematically observed the first flowers on the top branches in-curved to grow horizontally, while on ichangensis, its hybrids  and Thomasville it starts on the lower horizontal branches.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 12, 2021, 05:54:45 AM
Current photo of monofoliate Conestoga 058, the most Citrus-like in appearance of the original trial seedlings. this selection is vigorous and has good graft takes. It remains dormant a bit later in Spring, but grows too late into Autumn. I'm anticipating tasting this fruit when it transitions into mature phase. The leaves release a fragrant scent if they're bruised. A graft of this tree survived out doors last Winter, but had considerable cold damage.
(https://i.postimg.cc/R6nmwBRZ/Conestoga-058-nov-11-2021.jpg) (https://postimg.cc/R6nmwBRZ)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 18, 2021, 10:43:12 AM
5* Citrumelo in the center, with Poncirus+ on the left, and F2 Citranges on the right side.

Poncirus+ is showing strong deciduous habit. The F2 Citranges are variable from fully deciduous to strongly evergreen. 5* is the most persistent evergreen of all the hybrids I have at this point.

(https://i.postimg.cc/Tyjvj0ty/5-star-Citrumelo-evergreen.jpg) (https://postimg.cc/Tyjvj0ty)

Taitri seedling showing deciduous habit.TaiTri is inconsistent, with some trees being persistent, while others are rather freely deciduous. The tall, slender growth habit and similar narrow, long leaves of TaiTri initially led me to suspect they were nucellar seedlings. However, they vary in deciduousness, hardiness (some tops are already cold damaged, while others show no damage). There are also nuanced variations in branching and foliage.

(https://i.postimg.cc/0rMZLjqn/Tai-Tri-variable.jpg) (https://postimg.cc/0rMZLjqn)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on November 18, 2021, 12:14:04 PM
"Taitri seedling showing deciduous habit.TaiTri is inconsistent, with some trees being persistent, while others are rather freely deciduous. The tall, slender growth habit and similar narrow, long leaves of TaiTri initially led me to suspect they were nucellar seedlings. However, they vary in deciduousness, hardiness (some tops are already cold damaged, while others show no damage). There are also nuanced variations in branching and foliage."

That's great to know.  Seedlings look alike and I assumed they were nucellar.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on November 18, 2021, 01:56:38 PM
because of the uniformity, i also suspected that they are most likely clones. very good to know.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 18, 2021, 02:58:15 PM
I agree with the observation that there's a lot of conformity. To be more certain they should be tested with a pollen donor that's very distinctive. If my seedlings are indeed clones, I will have more than I need, due to limited cold frame space. At present my plants are becoming quite crowded. An Arctic Blast might quickly cure that issue!
Title: Re: F2 citrange winter hardiness trial
Post by: Perplexed on November 18, 2021, 04:00:45 PM
If you need help getting rid of some taitri for space im here  ;D
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on November 19, 2021, 03:53:24 AM
@kumin  It's good when a cure is so easy to reach ;D
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 19, 2021, 04:31:27 AM
Mikkel, root separation becomes very difficult as closely planted trees grow larger. Within pots, jets of water can remove the soil, making the task somewhat easier. In the ground, not so easy.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 24, 2021, 04:11:07 PM


Taitri seedling showing deciduous habit.TaiTri is inconsistent, with some trees being persistent, while others are rather freely deciduous. The tall, slender growth habit and similar narrow, long leaves of TaiTri initially led me to suspect they were nucellar seedlings. However, they vary in deciduousness, hardiness (some tops are already cold damaged, while others show no damage). There are also nuanced variations in branching and foliage.

(https://i.postimg.cc/0rMZLjqn/Tai-Tri-variable.jpg) (https://postimg.cc/0rMZLjqn)
[/quote]

Upon closer observation, I need to retract the statement that TaiTri shows considerable variability. Upon closer inspection I see that the differences in leaf yellowing in preparation for leaf drop is now minimal. I looked at photos of the very young seedlings, there's a bit of difference, but much less than as apparent in the F2 citrange seedlings. I now must agree with other members who came to the conclusion that TaiTri is largely nucellar.

Lots of conformity, with an exception or two.
(https://i.postimg.cc/cgRQ0xWf/Tai-Tri-seedlings.jpg) (https://postimg.cc/cgRQ0xWf)

Another example of similarity among seedlings
(https://i.postimg.cc/QKNWDc0r/Tai-Tri-seedlings-2019.jpg) (https://postimg.cc/QKNWDc0r)

TaiTri seedlings on the left side, a bit older, .
(https://i.postimg.cc/RNDnr6tj/Tai-Tri-seedlings-on-left.jpg) (https://postimg.cc/RNDnr6tj)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on December 08, 2021, 11:40:21 AM
An additional tree has transitioned into mature phase. This tree is A-26 one of the cold trial F2 segentrange survivors and is presently 44 months old, will be 4 years old in April 2022. Yesterday I noticed it had flower buds waiting for next Spring, but overlooked the small immature fruit. These fruit must be from very late flowers and have no chance of maturing. However, they're a welcome sight as they indicate the tree is of fruiting age.

This tree is 11' high (3.35m) and the top had begun to lean sideways a bit. I'm leaning (pun) toward thinking treetops over 9' in height being directed to grow at a 90 deg. angle to the side might enhance early flowering. I doubt it's effective at a lower height.

Flower bud set to bloom in the coming Spring. Flower buds are more plump than vegetative buds.
(https://i.postimg.cc/sv6jjhsB/Flower-Bud-A-26.jpg) (https://postimg.cc/sv6jjhsB)


The tree developed short twigs in preparation for flowering, very similar to Poncirus fruiting twigs. This tree exhibits many Poncirus-like traits.
(https://i.postimg.cc/Rqv4wR06/Fruiting-twigs-A-26.jpg) (https://postimg.cc/Rqv4wR06)


Both fruits are visible in this photo, the smaller one is in the lower left near the pipe.
(https://i.postimg.cc/jn21ZC99/2-immature-fruits-A-26-Dec-2021.jpg) (https://postimg.cc/jn21ZC99)

Due to this tree being deciduous, I may attempt to cross it with 5* citrumelo in the Spring, I expect some of the Poncirus+ trees to also bloom in the Spring, giving additional opportunities for hybridization.
Title: Re: F2 citrange winter hardiness trial
Post by: BorisR on December 08, 2021, 02:08:36 PM
These fruit must be from very late flowers and have no chance of maturing.
Hello kumin! The fruit looks yellow in the photo. Maybe they are ripe?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on December 08, 2021, 03:12:04 PM
It's probably a cold response. The growth hasn't been enough to develop a smooth rind. Late blooming Poncirus develops similar fruit, small in size, rough in texture and yellowish-green in color. The immature poncirus are about 25% of the weight of fruit originating from Spring flowers. However, I will pick these segentranges to determine the presence of seeds. I rather doubt any seeds would be viable , but if so, a test for zygotic seeds would be in order.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on December 31, 2021, 09:54:18 AM
A-026 segentrange fruit's flesh is rather dry after freezing several times. It's very small, hopefully due to late season flowering. The color is deeper orange than Poncirus, The peel is less adherent than Poncirus, similar to sweet orange. Some Poncirus bitterness is apparent in the flesh, as well as the rind, but less intense than straight Poncirus . Unlike Poncirus, some sweetness is detectable. Next year I hope to get a better chance to evaluate mature fruit. The seeds are likely at least partially polyembryonic. I plan to do a seedling test for zygotic seedlings in a few weeks. At this point I know that the tree is pollen and seed fertile. This tree is deciduous and in the hardiest 5-6 of the seedlings. Hopefully, as more seedlings flower and fruit some will show better size.
(https://i.postimg.cc/hJzj9K2J/Dec-31-2021-A-026-segentrange-peel.jpg) (https://postimg.cc/hJzj9K2J)

(https://i.postimg.cc/4K9cXvkF/Dec-31-2021-A-026-segentrange-seeds.jpg) (https://postimg.cc/4K9cXvkF)

(https://i.postimg.cc/67n8k9nk/Dec-31-2021-A-026-segentrange-flesh-jpg.jpg) (https://postimg.cc/67n8k9nk)

A young grafted A-026 tree out of doors.
(https://i.postimg.cc/67xSXznq/PXL-20211120-133741545-MP.jpg) (https://postimg.cc/67xSXznq)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on December 31, 2021, 06:44:31 PM
That is very encouraging, a hardy deciduous F1 plant with improvement in fruit and only 4 seeds. 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 01, 2022, 03:58:01 AM
A-026 is actually an F-2 seedling of C 35 Citrange, itself a hybrid of Ruby blood orange and Poncirus.
Title: Re: F2 citrange winter hardiness trial
Post by: orangedays on January 01, 2022, 03:51:34 PM
Nice color! Congratulations, this is good progress towards your goals, and in only four years.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on January 01, 2022, 05:11:17 PM
Congratulation Kumin, first ripe fruits from your cross, looks encouraging.
Regards Frank
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on January 03, 2022, 08:15:08 AM
I think even small improvements over Trifoliate fruits are still a huge step forward if you consider that your Citranges have almost the same hardiness as Trifoliate. It is really impressive that you achieved this in a relatively short time I am looking forward to your next report...
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on January 03, 2022, 10:04:42 PM
A-026 is actually an F-2 seedling of C 35 Citrange, itself a hybrid of Ruby blood orange and Poncirus.

Interesting, Morton, Rusk and Thomasville all have Ruby parentage
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 06, 2022, 05:07:20 PM
This week's outdoor photos showing responses to cold weather to this point Jan 06, 2022

(https://i.postimg.cc/2bG4Ykqd/001-Citrange-A.jpg) (https://postimg.cc/2bG4Ykqd)
Citrange 001: One of the hardiest trees, initially evergreen, becomes deciduous with age.

(https://i.postimg.cc/XppwM0nF/001-Citrange-B.jpg) (https://postimg.cc/XppwM0nF)
Another Citrange 001

(https://i.postimg.cc/BtwKBw2v/006-Citrange-A.jpg) (https://postimg.cc/BtwKBw2v)
Citrange 006 Deciduous and quite hardy.

(https://i.postimg.cc/MvMjPbYm/006-Citrange-B.jpg) (https://postimg.cc/MvMjPbYm)
Another 006

(https://i.postimg.cc/zH3R1nY5/006-Citrange-C.jpg) (https://postimg.cc/zH3R1nY5)
Another 006

(https://i.postimg.cc/JthXJWDg/006-Citrange-D.jpg) (https://postimg.cc/JthXJWDg)
Additional 006

(https://i.postimg.cc/bG8DvXfm/010-Citrange-A.jpg) (https://postimg.cc/bG8DvXfm)
010 Among the hardiest

(https://i.postimg.cc/gwDwXMYm/011-Citrange-A.jpg) (https://postimg.cc/gwDwXMYm)
011 tetraploid and very hardy

(https://i.postimg.cc/MMpnyyTR/011-Citrange-B.jpg) (https://postimg.cc/MMpnyyTR)
Another 011

(https://i.postimg.cc/1fqfcR9W/024-Citrange-A.jpg) (https://postimg.cc/1fqfcR9W)
024 Evergreen when young.

(https://i.postimg.cc/qNrMs8DR/024-Citrange-B.jpg) (https://postimg.cc/qNrMs8DR)
Another 024

(https://i.postimg.cc/D4byg5KW/024-Citrange-C.jpg) (https://postimg.cc/D4byg5KW)
Additional 024

(https://i.postimg.cc/WtQ43RM0/028-Citrange-A.jpg) (https://postimg.cc/WtQ43RM0)
028: Failure: all the 028 plants are in poor condition
(https://i.postimg.cc/Lq697mpF/028-Citrange-B.jpg) (https://postimg.cc/Lq697mpF)
Another 028: failure

(https://i.postimg.cc/xXPjtcBP/054-Citrange-A.jpg) (https://postimg.cc/xXPjtcBP)
054 Rather good condition. Some bark splitting.

(https://i.postimg.cc/1gCm1bmn/067-Citrange-A.jpg) (https://postimg.cc/1gCm1bmn)
067: most Citrus-like in this test, high grafted on Poncirus, showing a bit of stress. Second year graft.

(https://i.postimg.cc/Bj2PsSk8/5-Citrumelo-A.jpg) (https://postimg.cc/Bj2PsSk8)
5* Citrumelo: looking okay at this point. High grafted on Poncirus. Second year graft.

(https://i.postimg.cc/YLgMg91Y/A-026-Citrange-A.jpg) (https://postimg.cc/YLgMg91Y)
A-026 acceptable hardiness, this selection is the first of the Citranges to flower and fruit.

(https://i.postimg.cc/CB9wzDfw/D-Citrange-A.jpg) (https://postimg.cc/CB9wzDfw)
D Citrange: hardiness is variable, late growth is cold sensitive, mature growth is quite hardy.

(https://i.postimg.cc/rDgc57tn/Original-Test-Plot.jpg) (https://postimg.cc/rDgc57tn)
2 Survivors in the original test plot. Unnamed at present, one is fully deciduous, one is evergreen.

(https://i.postimg.cc/9DcCRczw/Tai-Tri-Citradia-A.jpg) (https://postimg.cc/9DcCRczw)
Outdoor TaiTri high grafted on Poncirus. Second year graft.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on January 08, 2022, 11:58:07 AM
This is fascinating, how cold has it gotten so far?  Looking forward to seeing how well they make it though the rest of the winter. 

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 08, 2022, 12:58:16 PM
The lowest temperature to date was 9F (-12.7C) this morning. Snow cover often leads to lower temperatures, as we got our first snow yesterday. The previous lows were 17F (-8.3C). Being located in a semi rural area, official low temperature forecasts are unreliable on calm, windfree mornings.
We will be entering the time of year that's most challenging to overwintering plants. Frozen soil, increasing windiness, as well as increased sunshine will cause more damage than the weather has done up to this point.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2022, 03:01:54 PM
A-026 seedlings starting to emerge. Uncertain what percentage are nucellar.
(https://i.postimg.cc/9zYGPqnd/PXL-20220126-192620869.jpg) (https://postimg.cc/9zYGPqnd)

Small germination box with thermostat probe in one of the pots to prevent overheating. There's a heating mat on the bottom with heavy aluminum baking trays on top of the mats to keep the heat distribution uniform. Thermostat setpoint is 86F. (30C).

(https://i.postimg.cc/0b3r7kPG/PXL-20220126-192722396.jpg) (https://postimg.cc/0b3r7kPG)
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 28, 2022, 03:45:06 PM
Sounds like a good set up.  This year I've just put seeds in 72 cell trays and put them on top of the refridgerater.  It has worked ok. but there is only room for 4 trays at a time.  Nrxt year will be better.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 22, 2022, 07:03:56 PM
Recent photo of #002 segentrange showing minimal thorniness. There are a few short thorns present on some branches. This seedling has good hardiness. It is more difficult to get good "takes" when grafting this selection. The tips of the leaflets have a notched indentation.
(https://i.postimg.cc/hJG559Dw/PXL-20220220-153817819.jpg) (https://postimg.cc/hJG559Dw)

#128 a deciduous outdoor survivor showing no damage after repeated lows of 5F (-15C). Although trifoliate, it has uniquely shiny leaves during summer.

(https://i.postimg.cc/njbwcNY8/PXL-20220222-175604696.jpg) (https://postimg.cc/njbwcNY8)

Glossy leaves on #128 segentrange.
(https://i.postimg.cc/jDnXwZjR/PXL-20211025-171000870.jpg) (https://postimg.cc/jDnXwZjR)


A Meyer lemon seedling showing the effects of repeated low temperatures in the cold frame.
The trifoliate leafed tree in the upper left corner is a 5*Citrumelo.
(https://i.postimg.cc/2q2Vzffy/PXL-20220216-140622248.jpg) (https://postimg.cc/2q2Vzffy)
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on February 23, 2022, 01:11:27 AM
very interesting your different crossing varieties, which shows a really good success for frost hardiness and perhaps more interesting fruits than poncirus. Also very interesting your Meyer seedlings, which lows did they take in the last winters ?  Because I also have one year old Meyer seedlings and thought about planting them testwise in open ground in zone 7 not sure if they will survife  a middle winter ? But waiting 10 years for fruit or rootstock are no good alternatives  ;).
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 23, 2022, 02:00:49 AM
Tedburn, the previous Winters may have had temperatures at -10C in the cold frame for a short duration. This Winter has been both colder and the cold period has been of longer duration. I used frost cloth for protection until this year. The trees are much too tall to cover at present, unless it were installed at roof height. The Meyer was included simply for comparing the F2 selections to standard Citrus. It's serving it's purpose.
You bring up a good point in looking at optimistic outcomes vs realistic outcomes. For me it boils down to a goal of Citrus fruits on Poncirus trees. The question is how soon and how close that rather lofty goal might be achieved.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on February 23, 2022, 11:53:58 AM
Kumin, thanks for your reply, and I fully understand and support your goal for citrusfruit on poncirustree.
But for me it still would be interesting to which low temperature your meyer seedlings could withstand without getting died by freeze, only as orientation, because as far as I know meyers should die by freeze below - 6 C as different sources mention, I didn' t freeze tested them.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 23, 2022, 12:18:14 PM
Past years aren't a good reference, as I used 4 layers of frost cloth. That should have trapped warmth underneath. So based on this Winter, my recollection is that the first sign of leaf damage was around -5C. Subsequent cold nights added to the damage, even at similar temperatures. I didn't pay a great deal of attention to it as Meyer lemon is peripheral to my interests. If I had to give a response, I would suggest that the severe damage coincided with the surface of the soil freezing.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on February 23, 2022, 01:53:24 PM
Thanks Kimun, so this confirms that meyer is concerning freezes very limited.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 25, 2022, 05:01:48 PM
At least 2 of my 5 Poncirus+ 3 year old seedlings will be flowering this year. Hopefully, there'll be some fruit setting. There will be quite a few A-026 flowers on a 4 year old seedling.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 25, 2022, 05:43:01 PM
This is impressive!
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on March 26, 2022, 01:47:01 AM
very nice such early flowering 👍. What are the secrets if this early flowering ? I assume all your plants are in open ground ?  So what are the other parameters for early flowering of seedlings ? Regards Frank
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 26, 2022, 06:27:15 AM
The plants are in an unheated cold frame. The plastic film at the ends of the structure is removed during the Summer. Nevertheless, the inside temperatures are higher than the outside temperatures. Additionally, I feed with foliar fertilizer during the Spring and Summer, but not Autumn, as late growth is susceptible to Winter freeze damage.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 26, 2022, 01:26:20 PM
I assume all your plants are in open ground ? Frank
The large plants are in open ground. Last Summer's grafts are in pots. Only the trees planted in the soil are flowering, and only a few of them are flowering this Spring. The trees in the cold frame are 2-3 times as tall as the outdoor plants, but less stocky, the increased node counts likely contribute to the precocity.
My guess is that a number of additional plants will transition to mature phase this Summer.
The next several nights are forecast to have near record low temperatures, some as low as -6,6C (20F). This might be challenging, as there's some early bud-break.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on March 26, 2022, 02:19:52 PM
Thanks Kumin for the explanation  :D, we also had now more than 2 weeks of challenging weather, days with 15 C and more and nights or mornings down to -5 C, so I akso had to cover the plants in pots already on terrace with flees to protect the already growing buds. But now freeze us finished for the next days.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 03, 2022, 05:31:01 PM
A-026 segentrange twigs full of flower buds. This tree is 4 years old this month. The seeds are nucellar, but the pollen should be fertile. This tree flowered last summer and is the first to fruit.
(https://i.postimg.cc/dhkYYtDH/PXL-20220403-204354087-MP.jpg) (https://postimg.cc/dhkYYtDH)

Flower buds on the 3 year old Poncirus+ seedlings, 3 out of 5 seedlings are ready to flower, but may not all have pistils in the flowers.
(https://i.postimg.cc/t1FGsS3F/PXL-20220403-204532997.jpg) (https://postimg.cc/t1FGsS3F)

Nucellar A-026 seedlings from last summer's fruit.
(https://i.postimg.cc/zVSN7X34/PXL-20220403-213351204-MP.jpg) (https://postimg.cc/zVSN7X34)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 13, 2022, 07:13:21 PM
2 additional trees from the outdoor trial in 2018/2019 have produced flowers:

(https://i.postimg.cc/ctYzKBvq/Conestoga-010-flowers.jpg) (https://postimg.cc/ctYzKBvq)
Conestoga 010 with flower buds, not certain if these will have pistils and ovaries or only anthers. This selection is among the very hardiest.

(https://i.postimg.cc/v4P0ZN0g/Conestoga-A-026-flowers-2.jpg) (https://postimg.cc/v4P0ZN0g)
Conestoga A-026 is blooming prolifically. This tree produces seeded fruit, but all seeds appear to be nucellar. Pollen is fertile, however.

(https://i.postimg.cc/hQbrWyJG/conestoga-006-flower.jpg) (https://postimg.cc/hQbrWyJG)
Conestoga 006 first flower, unfortunately there's no pistil in the flower. Not unusual for first flowers. This selection is very slightly less hardy than Conestoga 010 and 011.

(https://i.postimg.cc/4YF1gh3p/Poncirus-flower.jpg) (https://postimg.cc/4YF1gh3p)
Poncirus+ flowers, being the first flower, about 80% are missing the pistils.

An observation regarding Conestoga 001 and 058: these 2 selections don't have the Winter bud scales present on Poncirus. Conestoga 001 is very hardy and reluctantly deciduous as the trees grow larger. Conestoga 058 is the most Citrus like. evergreen and the least hardy, but quite vigorous. Since these 2 selections lack scaly Winter buds, I expect them to flower during the initial Spring flush as conventional Citrus does.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on April 14, 2022, 01:36:11 AM
congratulation to your breeding success and the early flowering plants and thank you for your very interesting reports 👍
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 14, 2022, 05:08:32 PM
You really seem to have the right conditions for Poncirushybrids. Congratulations! I'm very excited to see how it goes.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 14, 2022, 06:01:45 PM
Mikkel, with the limited amount of flowering options at present, I'm using Poncirus+ as a seed parent and Conestoga 006 and A-026 as pollen parents in crosses at the present time.. Conestoga 010 should be flowering within about a week and could potentially be another parent. I also have thousands of regular Poncirus buds within a week of blooming, but might not use, except potentially as seed parents.
Differentiating between 100 % Poncirus and 75-80% Poncirus might be quite a challenge!
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 14, 2022, 09:29:33 PM
The grafts your F2 citranges you sent last summer are showing new growth today.  They n were not exposed to a trae Kansas winter.  They were protected from the worst.  But they went dprmant,
Too soon to know if they will bllom.
I'm wanting to graft each to my  8 year old Korean Pt.  While Pennsylvania and Kansas are both zone 6, there are differences in daily temperature fluctuations etc,
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 18, 2022, 07:08:08 PM
Hopefully, we're getting close to our last freezing weather. There is no apparent recent cold damage at this point.
This morning's low temperature was 26F, I started the sprinkler system at 1:00 AM during the night. There was a heavy accumulation of ice, but everything looks fine.
(https://i.postimg.cc/MvcYKRwC/PXL-20220418-130622268.jpg) (https://postimg.cc/MvcYKRwC)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 20, 2022, 01:51:44 AM
You really seem to have the right conditions for Poncirushybrids. Congratulations! I'm very excited to see how it goes.

Mikkel, I would attribute the adaptation of these hybrids to the severe selection pressure presented by the survival of several dozen individual trees out of 20 000 original seedlings.
In a sense, it's an accelerated form of the natural selection process. In nature these processes are constantly driven by disease and other environmental factors. In this case the predominant factor is cold temperatures.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 20, 2022, 11:50:24 AM
Natural selection can be pretty intense. On the average, in the wild, each tree gives only one seedling to reach maturity. 
Otherwise the number of trees would keep increasing.
But in the wild, many of the seedlings die by being eaten by insects and bigger animals, not for lack of adaption.  Of course, in Kumin's program, dangers other than cold were eliminated.  So all the selection was limited to cold survival.  That's what breeders do.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 24, 2022, 06:15:44 PM
A few updates since we have had low temperatures of 26F. Some of the trees are planted in the lowest location of the property and suffered frozen newly emerged buds.
(https://i.postimg.cc/z3J9fkkq/PXL-20220424-130030309-NIGHT.jpg) (https://postimg.cc/z3J9fkkq)
# 010 frozen buds at ground level, no damage higher on the plant.



(https://i.postimg.cc/HJdtt6nx/PXL-20220424-125937101-NIGHT.jpg) (https://postimg.cc/HJdtt6nx)
#011 damage only at the lowest locations, hardiness essentially identical to #010.


(https://i.postimg.cc/PPDzsg8J/PXL-20220424-214552545.jpg) (https://postimg.cc/PPDzsg8J)
#001 very little damage.


(https://i.postimg.cc/yDPR7s61/PXL-20220424-214901583-MP.jpg) (https://postimg.cc/yDPR7s61)
4 year old #128 no damage on own roots, slightly higher elevation (20"-24" higher). The majority of the survivors in the original test plot were severely damaged during the past Winter. This tree shows not damage and is clearly hardier that the others.


(https://i.postimg.cc/q6sRQxzJ/PXL-20220424-215446063-MP.jpg) (https://postimg.cc/q6sRQxzJ)

Poncirus in full bloom, higher elevation, no damage.

The most important determining factor appears to be elevation, in previous years Poncirus showed damage of about the same degree as the hybrids, determined by elevation on clear,  wind free nights.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 01, 2022, 06:03:13 PM

(https://i.postimg.cc/wyGXVfQx/PXL-20220429-180628606.jpg) (https://postimg.cc/wyGXVfQx)
4 year old Segentrange showing a number of post bloom fruitlets. This tree produced 2 June bloom fruits last year.  Unfortunately, the seeds appear to be nucellar.
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on May 05, 2022, 05:32:47 AM
Nice fruits, looks like the flower buds are the same type as on Poncirus, did you try flowers if they are fragrant or without smell as Poncirus flowers?
Fruitless are also hairy like Poncirus, let's hope they will have somehow better taste  :) I am looking forward to your next information... 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 05, 2022, 12:02:27 PM
Jibro, you're correct, these flowers bloom from Poncirus type fruit buds that develop in the previous Summer. None of these flowers are fragrant. A-026 fruit are subtilty sweet. Two of the Segentranges that haven't flowered yet have fragrant leaves, hopefully their flowers will also be fragrant.

By undergoing extreme selection for cold hardiness, it can be expected the survivors will be skewed towards Poncirus genetically.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 16, 2022, 07:19:25 PM
Another 5* Citrumelo tree is in bloom at 37 months of age. Most of these flowers are staminate, but are loaded with pollen.
(https://i.postimg.cc/HjJJZsTR/PXL-20220516-225509522-MP.jpg) (https://postimg.cc/HjJJZsTR)

The outdoor, high grafted on Poncirus, 5* was injured by repeated lows of +5F. temperatures. 5* is a vigorous grower and should recover nicely.
(https://i.postimg.cc/kD8JRVJJ/PXL-20220516-160910712-MP.jpg) (https://postimg.cc/kD8JRVJJ)

TaiTri finally appears to be a bit hardier than 5* Citrumelo.
(https://i.postimg.cc/qNCVSSNk/PXL-20220516-160922575.jpg) (https://postimg.cc/qNCVSSNk)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 20, 2022, 07:50:50 PM
(https://i.postimg.cc/qNjbkxKP/PXL-20220601-125406839-PORTRAIT.jpg) (https://postimg.cc/qNjbkxKP)
Conestoga A-026 fruit have set quite reliably. The size likely won't exceed the size of Poncirus. These fruits were self-pollinated, as they appear to produce nucellar embryos.
(https://i.postimg.cc/7fVJr38D/PXL-20220620-235300481-MP.jpg) (https://postimg.cc/7fVJr38D)
A large number of Poncirus flowers were pollinated with Meyer lemon pollen. The setting percentage was excellent.
(https://i.postimg.cc/BtfgCfxz/PXL-20220620-235344301.jpg) (https://postimg.cc/BtfgCfxz)
Meyer lemon fruits pollinated with Poncirus+ and 5* Citrumelo pollen. All the seedlings should be hybrids.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 21, 2022, 03:05:08 AM
Meyer lemon fruits pollinated with Poncirus+ and 5* Citrumelo pollen. All the seedlings should be hybrids.
From my experience Meyer's flowers should be castrated very early since it shedding pollen well before flower bud opening.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 21, 2022, 04:19:02 AM
Ilya, I also noticed Meyer releasing pollen before the petals opened. To prevent self pollination the petals were opened with tweezers and the anthers were extracted a day or two before the petals opened naturally. The pistils didn't appear to be receptive when the anthers were removed, so the pollination was repeated 2-3 times over the following days.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 21, 2022, 10:31:35 AM
Kumin,
Do you have an experience with Meyer hardiness?
 In US it is considered more hardy than regular lemons, but strangely enough, when I tested several Meyer clones available here in Europe, they all turned out to be  less resistant than Eureka.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 21, 2022, 03:18:28 PM
I have 2 Meyer seedlings in the cold frame as a control comparison against my other hybrids. At 20F (-6.6C) in the 2020/2021 Winter there was no damage. During the immediate past Winter (2021/2022) at 15F (-9C) they were severely damaged and haven't recovered yet. We have the issue of repeated low temperatures, unlike the Southern US, which tends to have shorter intervals of cold weather. 
All of my Poncirus hybrids are more cold resistant than Meyer lemon.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 09, 2022, 03:31:33 PM
400+ Outdoor trees, Segentrange hybrids, as well as Poncirus rootstock in waiting for high grafting.

In addition to Segentranges, there are 5* Citrumelos and Taitri trees grafted on Poncirus in this planting. Some of these selections are proven survivors, others are planted for Winter testing. Not all will survive!
(https://i.postimg.cc/c6xxJxcK/July-9-i.jpg) (https://postimg.cc/c6xxJxcK)

Good fruit set on Poncirus, many of these fruits are pollinated by Meyer lemon pollen. These trees are consistant producers of larger, juicy fruits. Seediness is not less, but the larger fruit provides more space for flesh. These were sourced from the late Major B. Collins of Tifton, Georgia USA, a cold hardy Citrus enthusiast.
(https://i.postimg.cc/ZBVhNNLW/Poncirus-July-9-2022.jpg) (https://postimg.cc/ZBVhNNLW)


(https://i.postimg.cc/ykvJWhG5/PXL-20220711-170044599.jpg) (https://postimg.cc/ykvJWhG5)
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on July 10, 2022, 01:11:43 AM
very interesting, I also like meyer lemon as a good often flowering and fruiting plant. Curios to the winterhardiness of poncirusmeyer  :D
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 25, 2022, 10:10:18 AM
3 year old 5 star citrumelo seedlings showing fruits, many of these result from summer flowers, which may not ripen by late October.

(https://i.postimg.cc/3yrVM1QP/zzzzz.jpg) (https://postimg.cc/3yrVM1QP)

(https://i.postimg.cc/ykqG6szh/zzz.jpg) (https://postimg.cc/ykqG6szh)

(https://i.postimg.cc/NyLD7zcf/cccc.jpg) (https://postimg.cc/NyLD7zcf)

(https://i.postimg.cc/jn64SVzv/5-star-citrumelo-july-25-2022-z-jpg.jpg) (https://postimg.cc/jn64SVzv)


Title: Re: F2 citrange winter hardiness trial
Post by: Walt on July 25, 2022, 12:14:05 PM
I wonder how far along a citrus seed has to be to be viable.  Barley seeds are viable at 2 weeks post pollination, even though the seed coat looks pretty empty.
Do you have plans to extend the season by covering the mother plants for a while?
Have you thought about embryo culture if the seeds are too immature?
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on July 25, 2022, 12:37:28 PM
Highest success rate with embryo culture was at 95 days post pollination. 
If they don't look like there will be viable seeds and you don't want to cover the mother plants and don't want to set up an embryo culture lab (not as hard as it sounds), you could send me the fruits and I could try.  I have never embryo cultured anything but barley and iris.  But it is much the same.

https://mdpi-res.com/d_attachment/agronomy/agronomy-10-01940/article_deploy/agronomy-10-01940.pdf?version=1607580009

This paper is on using embryo culture to rescue hybrid embryos in crosses that produce lots of nucellar embryos.  Having only one embryo per seed should make it even easier.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 25, 2022, 12:58:30 PM
The first 2 photos are less likely to produce mature embryos, as they're still in bloom. The last 2 photos may actually be from Spring bloom and stand a chance of producing mature seeds.

Last year Conestoga A-026 produced viable seeds, which were 100% nucellar. The 5* seeds were very soft and immature. I'll get in touch with you later in the season if embryo rescue appears to be feasible.
I'm seeing a few Poncirus+ fruitlets, which will give me an opportunity to evaluate their taste. There are a number of A-026 fruits from Spring bloom,  which should allow me to better assess their real, mature flavor. A-026 survived the past Winter out of doors, with damage on the smallest trees only.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 08, 2022, 11:52:32 AM
(https://i.postimg.cc/zbNFZfg3/PXL-20220808-124214748.jpg) (https://postimg.cc/zbNFZfg3)
5* Citrumelo is not a shy fruit bearer. 3 year old tree.

(https://i.postimg.cc/dhK19TP7/PXL-20220808-124810995.jpg) (https://postimg.cc/dhK19TP7)
Conestoga 058 is a vigorous grower, but hasn't fruited to this point. 4 year old tree.



(https://i.postimg.cc/WtvqnKGp/PXL-20220808-124648031.jpg) (https://postimg.cc/WtvqnKGp)

Conestoga A-026 Segentrange recent photo of fruit. 4 year old tree.

(https://i.postimg.cc/tYbQSdJH/PXL-20220808-124814830.jpg) (https://postimg.cc/tYbQSdJH)

Upper branches of Conestoga 058, largely monofoliate. 4 year old tree - no fruit yet.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 18, 2022, 03:22:21 PM
As the seedlings mature, it's clear that they're segregating for precocity among other characteristics. Both grapefruit and sweet orange are known for long periods of juvenility, yet there are F2 citrange and citrumelo seedlings segregating for precocity in both populations. I am seeing a number of 2, 3, and 4 year old trees flowering and fruiting while sibling progeny are not yet flowering, nor fruiting. Selecting these precocious plants may be helpful as parents in further breeding.   
Title: Re: F2 citrange winter hardiness trial
Post by: 1rainman on August 18, 2022, 08:25:20 PM
Here in Florida we can get nights as cold as 20 F maybe even slightly lower like 15. Though we haven't had low temps like that in many years and it warms up quickly during the day.

Do not use lemons to cross. They are not cold hardy, except meyer lemon. Navel oranges are cold hardy to these temps (though typically on a cold hardy root stock). Tangerines are more cold hardy than oranges, they are similar to navel oranges, maybe better. Grapefruit is the most cold hardy citrus that is good to eat and tangelos (half grape fruit half tangerine) are also very cold hardy almost the same as a grapefruit in most cases).

It may be different in northern climates where the cold is sustained. Meyer lemon, tangelos and grapefruit grow well in cool weather (like 40 degrees during the day and below freezing at night). Those would be the best choices for making crosses: Meyer Lemon, Tangelos (like honey bell), and grapefruit (maybe ruby red or something). Though they would not be good in Pennsylvania. I would try them further south maybe Georgia or South Carolina. All the trifoliate crosses have always yielded inedible fruit. You would have to shrink the percentage of trifoliate genes to 1/4 or less.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 23, 2022, 06:05:26 PM

(https://i.postimg.cc/crdQrCdr/PXL-20220527-222644155-MP.jpg) (https://postimg.cc/crdQrCdr)
Segentrange showing the results of having stem hardiness, but lacking Winter bud scales. This selection shows no late Winter bark splitting, but has strong leaf distortion due to lack of protective Winter bud scales.

The first flush of leaves show disfigurement, subsequent flushes produce normal leaves.

There are many factors that influence cold hardiness.
1. deciduousness
2. dormancy early - Winter - Spring
3. season of fruit maturity
4. stem resistance to bark splitting
5. presence of Winter bud scales.
6. resistance to Winter stem dehydration
7. presence of first flush flowers developed from buds on previous Summer's growth - to get a early start on fruit maturity
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 24, 2022, 03:03:12 AM
Interesting.
Do you have  photos with winter bud scales and without them?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 24, 2022, 04:29:32 AM
Conestoga # 128 Segentrange showing winter bud scales.

(https://i.postimg.cc/bdBGPNdX/PXL-20220225-161422885-MP.jpg) (https://postimg.cc/bdBGPNdX)

(https://i.postimg.cc/wt8fGpDL/PXL-20220317-143100668.jpg) (https://postimg.cc/wt8fGpDL)
Prominent winter bud scales appear to be related to early and complete deciduousness. These trees suffer less dehydration than evergreen and reluctantly deciduous trees.

Conestoga #001 Segentrange. Reluctantly deciduous with stem hardiness, but shows some dehydration. Lacks prominent winter bud scales.
(https://i.postimg.cc/jCR7hdkP/PXL-20220424-214528673-MP.jpg) (https://postimg.cc/jCR7hdkP)




Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 24, 2022, 10:47:28 AM
Does this mean that outer scales are green in the case of #001 but brown/purplish colored for #128?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 24, 2022, 03:15:48 PM
Ilya, the prominent bud scales on #128 are indeed brownish in color.  The buds on #001 are smaller, flatter and the same green color as the stems. The large outer scales are missing on #001.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 25, 2022, 03:18:10 AM
Interesting, I checked now my plants and all of them including poncirus varieties have green scales that are not very prominent for the moment. 
When do you think the difference starts to emerge? At the leaf fall?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 25, 2022, 04:01:37 AM
Today's photos of a Conestoga #128 twig showing developing scale covered brown buds. This tree is strongly deciduous and has minimal late growth flushes.
128 has never been protected in any manner.

This tree hasn't flowered yet.
(https://i.postimg.cc/jCQtZYVD/PXL-20220825-152733338.jpg) (https://postimg.cc/jCQtZYVD)

(https://i.postimg.cc/S2LFTCvB/PXL-20220825-152710041-MP.jpg) (https://postimg.cc/S2LFTCvB)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 25, 2022, 02:30:20 PM
Not with my plants, could be more sun in your place.
I  suspects that this coloration could be due to the induction of anthocyanins that arrives in autumn  in poncirus leaves.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 26, 2022, 10:26:16 AM
Outdoor F Segentranges in late Summer.


(https://i.postimg.cc/ygWkRvzb/PXL-20220826-114035225.jpg) (https://postimg.cc/ygWkRvzb)
Conestoga 006 1 year since planting. On Poncirus rootstock. Flowered in May, no fruit set.

(https://i.postimg.cc/jDZxhPv0/PXL-20220826-114441127-PORTRAIT.jpg) (https://postimg.cc/jDZxhPv0)
Conestoga 011 tetraploid, no flowers to this point. Very hardy.

(https://i.postimg.cc/kV0kN5rP/PXL-20220826-114422481-PORTRAIT.jpg) (https://postimg.cc/kV0kN5rP)

Conestoga 010 very hardy, has flowered, no fruit set.

(https://i.postimg.cc/gwhYbQmd/PXL-20220826-114405556-PORTRAIT.jpg) (https://postimg.cc/gwhYbQmd)
Another 010

(https://i.postimg.cc/yWj7KF4J/PXL-20220826-114258378-PORTRAIT.jpg) (https://postimg.cc/yWj7KF4J)
Conestoga 001 semi-deciduous, initial Spring flush of leaves are distorted no bark splitting.

(https://i.postimg.cc/vgzwQdjR/PXL-20220826-114126962.jpg) (https://postimg.cc/vgzwQdjR)
A-026 Segentrange precocious and hardy. The original tree has flowered and fruited.
Title: Re: F2 citrange winter hardiness trial
Post by: 1rainman on August 28, 2022, 03:17:40 PM
How do you cross breed citrus considering they usually pollinate themselves
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on August 28, 2022, 03:53:57 PM
There is a lot of information here. You can read a little in older posts.
Many citrus plants are nucellar and thus simple clones of the parent tree, but there are also many varieties that are zygotic. However, nucellar trees will also produce some zygotic offspring.
For nucellar varieties, it depends on the number of seedlings to find the zygotic offspring
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 28, 2022, 07:12:03 PM
As Mikkel mentioned, hybridizing Citrus isn't necessarily as straightforward as most plants. Citrus can produce:

1. Nucellar embryos which develop into exact clones of the mother tree.

2. Zygotic embryos, containing genetic contributions from the seed parent, as well as the pollen donor parent, same as are normally found in the majority of plants.

3. Or commonly, a mixture of both types.

Citrus having exclusively nucellar embryos can serve as pollen parents. Citrus producing zygotic embryos can serve as either pollen, or seed parents. There are additional nuances such as pollen sterility (Satsuma), self incompatibility (Clementine tangor).

The actual breeding process involves removal (emasculation) of the pollen bearing anthers from the intended seed bearing flower before any pollen is shed(dehiscence). And protecting the flower from bee visitation, or accidental pollen introduction onto the receptive stigma.
 Pollen is collected from the intended pollen donor flower(s) free of contamination by extraneous pollen. This pollen is transferred onto the stigma of the emasculated seed flower. The stigma should produce a sticky film on it's surface when it's receptive to pollen. The pollinated flower is then identified and protected from additional unintended exposure to pollen until the stigma is no longer receptive.

Not ever breeder will follow ever step for the sake of saving time. Not every flower will produce a persisting fruit. Unpollinated flowers and  buds can be removed to increase fruit set among the control pollinated flowers. Removal of pre-existing fruit may also improve fruit set of the control pollinated flowers.
(https://i.postimg.cc/VSy60JC6/PXL-20220418-155624684.jpg) (https://postimg.cc/VSy60JC6)
The center of the flower showing the miniature fruit (ovary) behind the style and the small round stigma. The pollen grains germinate on the stigma and the sperm cells grow through the pistil into the ovary. Fertilization occurs in the ovary. Encircling the ovary are a ring of filaments topped by anthers. In natural pollination the pollen is transferred from anthers onto the stigma.
In controlled pollination unintended pollen is excluded from contact with the stigma, while the desired pollen is placed on the stigma by human intervention.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 27, 2022, 04:46:54 PM
With the onset of Autumn just beginning, I've noticed the Conestoga A-026 Segentrange fruits starting to break color. Hopefully they'll progress to a solid orange color by the time of ripening. The fruit size is just a bit larger than Poncirus and the shape perhaps more globose, but Poncirus is already quite round. The rind is smooth.
(https://i.postimg.cc/DJCmnDtg/PXL-20220927-121137024.jpg) (https://postimg.cc/DJCmnDtg)

(https://i.postimg.cc/4Ks3tsGP/PXL-20220927-121143023-MP.jpg) (https://postimg.cc/4Ks3tsGP)
Last year's fruit color on immature A-026fruits.

(https://i.postimg.cc/WqNZNgWG/PXL-20211231-133545438-MP.jpg) (https://postimg.cc/WqNZNgWG)

(https://i.postimg.cc/DWhw3FYs/PXL-20211231-133517886-MP.jpg) (https://postimg.cc/DWhw3FYs)

(https://i.postimg.cc/p5vdRvd3/PXL-20211231-133707178-MP.jpg) (https://postimg.cc/p5vdRvd3)


(https://i.postimg.cc/zbWBtb57/Dec-31-2021-A-026-segentrange-flesh-jpg.jpg) (https://postimg.cc/zbWBtb57)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on September 28, 2022, 03:42:44 AM
Kumin,
Are fruits of poncirus already ripe in your region?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 28, 2022, 05:33:51 AM
Ilya, Poncirus is also showing rind color transition, but is about 2-3 weeks from full ripeness. Within the cold frame there's Poncirus+ which is showing less color change than the A-026. The Poncirus+ fruits are much smaller, perhaps due to low seed count. A-026 blooms and sets fruit freely, but last year's seeds produced all nucellar seedlings.
I'm very interested in seeing what the taste of the A-026 fruit is upon ripening. I recall the peel having a degree of Poncirus flavors. Of greater interest is the taste of the flesh.

There are several hundred grafted young trees planted outdoors to further evaluate their Winter hardiness. I plan on using both anti desiccants and diluted white interior latex paint spray in December. The white paint will only be applied on the South side of the trees.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on September 28, 2022, 09:05:52 AM
Thank you,
But when PT was flowering this spring?
My plants usually flower at the middle of April, now fruits are almost entirely yellow.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 28, 2022, 09:41:25 AM
(https://i.postimg.cc/kBPDR656/PXL-20220424-215443946.jpg) (https://postimg.cc/kBPDR656)
Poncirus in full bloom on April 24th 2022.

(https://i.postimg.cc/mhk2c3Rg/PXL-20220928-134244797.jpg) (https://postimg.cc/mhk2c3Rg)
Poncirus fruits today. They're in the process of changing color. We are getting cool nights, which accelerates the color change.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on September 28, 2022, 11:11:18 AM
It seems that A-026 was in a frame, was it flowering also in April?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 28, 2022, 12:21:57 PM
It seems that A-026 was in a frame, was it flowering also in April?

Yes, Ilya, A-026 flowered a few days before outdoor Poncirus, but due to cool weather the blooming periods overlapped quite a bit. I suspect the warmer daytime temperatures in the cold frame hastened the blooming period by about 5-7 days.
The overlapping blooming periods allowed me to make a number of crosses.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 10, 2022, 10:18:04 AM
PoncirusPlus fruits beginning color transition. These fruits are unusually small and may have low seed counts. Nevertheless, there should be an opportunity to taste the fruit. These trees are 3 years old. 2 out of seven trees bloomed and fruited. All the fruits are undersized, but conditions were not ideal during the flowering period. However, Conestoga A-026 flowered successfully during the same period.


(https://i.postimg.cc/CZ7XBJCf/PXL-20221010-133025512.jpg) (https://postimg.cc/CZ7XBJCf)

5* Citrumelo fruitlets on 3 year old trees. These are the results of late Summer blooms. There are also fruit from Spring flowers, but they're obscured by vegetation, including thorns.
(https://i.postimg.cc/qhXfL4dg/PXL-20221010-134724453.jpg) (https://postimg.cc/qhXfL4dg)

(https://i.postimg.cc/DWkYYH6G/PXL-20221010-134743298-MP.jpg) (https://postimg.cc/DWkYYH6G)

(https://i.postimg.cc/fV36PxhG/PXL-20221010-134755820.jpg) (https://postimg.cc/fV36PxhG)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 30, 2022, 07:12:31 PM
First 5* Citrumelo mature fruit sampled on 3 year old trees. The fruit has just begun to change color. I didn't expect much of the fruit, but it was sweet as well as acid and had a noticeable grapefruit flavor. There was a bit of bitterness
similar to grapefruit. The fruit was approximately 4 cm (1 1/2") in diameter, quite small. The Brix was 12.
(https://i.postimg.cc/3dzrLSJq/PXL-20221030-191103659.jpg) (https://postimg.cc/3dzrLSJq)

(https://i.postimg.cc/MvnKm2xR/PXL-20221030-191225603.jpg) (https://postimg.cc/MvnKm2xR)
When high grafted onto Poncirus the scions have survived and recovered after a low of 5F (-15C) during the past Winter.
Title: Re: F2 citrange winter hardiness trial
Post by: tedburn on October 30, 2022, 07:18:20 PM
excellent result for 3 year old trees
Title: Re: F2 citrange winter hardiness trial
Post by: Florian on October 31, 2022, 04:10:41 AM
First 5* Citrumelo mature fruit sampled on 3 year old trees. The fruit has just begun to change color. I didn't expect much of the fruit, but it was sweet as well as acid and had a noticeable grapefruit flavor. There was a bit of bitterness
similar to grapefruit. The fruit was approximately 4 cm (1 1/2") in diameter, quite small. The Brix was 12.
(https://i.postimg.cc/3dzrLSJq/PXL-20221030-191103659.jpg) (https://postimg.cc/3dzrLSJq)

(https://i.postimg.cc/MvnKm2xR/PXL-20221030-191225603.jpg) (https://postimg.cc/MvnKm2xR)
When high grafted onto Poncirus the scions have survived and recovered after a low of 5F (-15C) during the past Winter.

Three years is very quick. Are you planning any mass trials with 5* too?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 31, 2022, 05:03:23 AM
I'm not planning on any mass trials, although it may be a great challenge, provided the percentage of zygotic seedlings is high enough to make it feasible. My plans are more along the lines of using it as a parent in crosses with Citrandarins of Changsha parentage as well as the selections from my Citrange Winter trials.
I suspect this tree is a zygotic seedling due to it's precocity.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 06, 2022, 02:51:07 PM
I've been able to taste test one fruit each of Poncirus Plus and Segentrange Conestoga 026.

Poncirus Plus:
More bitterness
Brix 11
Rind 4mm thick
Smaller fruit 7 seeds
Less wax
Acidic

Conestoga 026:
Brix 12
Low bitterness
2mm rind
More wax, but little taste to it
Acidic

When diluted with water and sweetened,I preferred the Conestoga 026 flavors.

(https://i.postimg.cc/RqpF7bMM/PXL-20221106-191706182.jpg) (https://postimg.cc/RqpF7bMM)
Poncirus Plus very small fruit due to inadequate foliage to support the fruit.

(https://i.postimg.cc/kRRdFsc4/PXL-20221106-191404471-MP.jpg) (https://postimg.cc/kRRdFsc4)
Poncirus Plus

(https://i.postimg.cc/N9V3MTcw/PXL-20221106-191251530-MP.jpg) (https://postimg.cc/N9V3MTcw)
Poncirus Plus


Conestoga 026
(https://i.postimg.cc/Z9N7cgkX/PXL-20221106-120600471-MP.jpg) (https://postimg.cc/Z9N7cgkX)
Conestoga 026
(https://i.postimg.cc/S2DW77Kw/PXL-20221106-120716121-MP.jpg) (https://postimg.cc/S2DW77Kw)
Conestoga 026
(https://i.postimg.cc/LqSfc0Yc/PXL-20221106-121433747.jpg) (https://postimg.cc/LqSfc0Yc)
Conestoga 026
(https://i.postimg.cc/CRTf86NR/PXL-20221106-123532845.jpg) (https://postimg.cc/CRTf86NR)
Conestoga 026 diluted with water.

(https://i.postimg.cc/phH5mPwG/PXL-20221019-155336140.jpg) (https://postimg.cc/phH5mPwG)
Conestoga 026 fruits
Title: Re: F2 citrange winter hardiness trial
Post by: Jibro on November 07, 2022, 05:14:02 AM
Nice report, can you add how big Conestoga fruits are or weight and how seedy they are on average?  Are Conestoga fruits ripen at the same time as poncirus or 1-2 weeks later? Thank you and congrats, I think even a small improvement compared to trifoliate fruits with the same hardiness as poncirus is good progress for people in USDA Zone 6.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 07, 2022, 05:38:09 AM
The fruit ripen at the same time as Poncirus and about 1-2 weeks before Poncirus Plus. The largest fruit was 5cm in diameter. The smaller ones about 4cm, not really larger than Poncirus. This may contribute to early ripening?
In regards to hardiness, there was a small amount of bark blistering in Winter on the southwest side. Dilute white latex spray on that quadrant of the trees may be helpful. As the trees grow larger it may not be an issue.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on November 07, 2022, 11:18:19 AM
ery encouraging results.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 07, 2022, 12:23:54 PM
Seed count from one 026 fruit. Seed count is higher than last year, but the fruit size is also larger. There are a few more empty seed coats than I found in Poncirus.
(https://i.postimg.cc/JyLzBbPF/PXL-20221106-120659704-MP.jpg) (https://postimg.cc/JyLzBbPF)
Title: Re: F2 citrange winter hardiness trial
Post by: Akebia on November 07, 2022, 02:55:25 PM
These F2 citranges should be more highly zygotic than the mother right?  Very encouraging progress. 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 07, 2022, 03:04:02 PM
Last year's fruit were very small having developed from a Summer bloom. All the seeds appeared to be nucellar. I saw no variation in the seedlings, but there may well be some in a larger population. The flowers contain adequate, viable pollen and could serve as male parents.
(https://i.postimg.cc/py5Pkyp7/PXL-20221107-211439093.jpg) (https://postimg.cc/py5Pkyp7)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 08, 2022, 08:57:24 AM
First 5* Citrumelo mature fruit sampled on 3 year old trees. The fruit has just begun to change color. I didn't expect much of the fruit, but it was sweet as well as acid and had a noticeable grapefruit flavor. There was a bit of bitterness
similar to grapefruit. The fruit was approximately 4 cm (1 1/2") in diameter, quite small. The Brix was 12.
(https://i.postimg.cc/3dzrLSJq/PXL-20221030-191103659.jpg) (https://postimg.cc/3dzrLSJq)

(https://i.postimg.cc/MvnKm2xR/PXL-20221030-191225603.jpg) (https://postimg.cc/MvnKm2xR)
When high grafted onto Poncirus the scions have survived and recovered after a low of 5F (-15C) during the past Winter.
I guess the fruit size will improuve with the age.
Below are the fruits from my 20 years old tree harvested today. The season was hot, 12 Brix, practically no perceptible internal oils, good lemonade when diluted three fold.

(https://i.vgy.me/Mhlbr2.jpg)

(https://i.vgy.me/ED2v7C.jpg)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 08, 2022, 11:56:35 AM
I've noticed all the fruits in the cold frame are rather small. I'm waiting for the outside trees to fruit. They may be larger.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 12, 2022, 12:42:19 PM
Due to impending freezes, most of the 5* and Poncirus Plus fruit have been harvested. Both have small immature fruits remaining on the trees.
(https://i.postimg.cc/DJ4KwxpG/PXL-20221112-172813627-MP.jpg) (https://postimg.cc/DJ4KwxpG)
Largest 5* Citrumelo.

(https://i.postimg.cc/cgvd8xCr/PXL-20221112-172824328.jpg) (https://postimg.cc/cgvd8xCr)
Most mature 5* Citrumelo


(https://i.postimg.cc/dh9sbNgt/PXL-20221112-172925992.jpg) (https://postimg.cc/dh9sbNgt)
Poncirus Plus fruits.

(https://i.postimg.cc/MMw2wNrr/PXL-20221112-193419713.jpg) (https://postimg.cc/MMw2wNrr)
Fruits off one 3 year old
5* Citrumelo tree. 2 fruits were removed earlier.
(https://i.postimg.cc/MXd2ks0d/PXL-20221112-194517112.jpg) (https://postimg.cc/MXd2ks0d)
Diluted and sweetened Conestoga 026 juice. Taste is similar to lemonade.
2 of the persons taking part of the taste test commented on hints of grapefruit flavor.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 23, 2022, 09:52:30 AM
Photos of a larger 5* Citrumelo found on a tree that was overlooked earlier.
(https://i.postimg.cc/0rVKtvXg/PXL-20221123-143800765.jpg) (https://postimg.cc/0rVKtvXg)

(https://i.postimg.cc/WhQ3K1My/PXL-20221123-141015421-MP.jpg) (https://postimg.cc/WhQ3K1My)

(https://i.postimg.cc/FfvKrCCg/PXL-20221123-143655830-RESTORED.jpg) (https://postimg.cc/FfvKrCCg)
3 year old Poncirus seedling with a small fruit. If this tree fruits again in the coming year, I may consider it somewhat precocious.
(https://i.postimg.cc/9DpqkNhS/PXL-20221123-152415513-MP.jpg) (https://postimg.cc/9DpqkNhS)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on November 28, 2022, 03:25:45 PM
you have a hand for precocious plants :)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 28, 2022, 05:10:34 PM
Having large populations likely contributes to encountering them. I also attribute encouraging early , tall growth to the transition from vegetative to reproductive phase in a shorter time. However, not all the seedlings responded in the same way.