Tropical Fruit Forum - International Tropical Fruit Growers

Citrus => Cold Hardy Citrus => Topic started by: Walt on December 18, 2017, 04:34:50 PM

Title: Long term cold hardy citrus breeding project
Post by: Walt on December 18, 2017, 04:34:50 PM
I've started a citrus breeding program about 3 years ago.  Goal is hardy edible citrus for zone 6.

The plan is to have 9 breeding populations, based mostly on P. trifoliata, oranges, and mandarins.  The populations are pop. 1, pure P. trifolata;  pop 2, 7/8 P. trifoliata 1/8 Citrus species, most orange and mandarin;  pop 3, 2/8 , 6/8 Citrus;  pop 4, 3/8 Citrus, etc, up to pop 9, 8/8 Citrus.
Pop 1 is to be only monoebryonic P. trifoliata x precocious P. trifoliata.  If the F1 isn't monoembryonic, then, it could take a couple more generations to give a monoembruonic, precocious P. trifoliata.  This will be useful in later breeding.
Pop9, at the other extreme, will be to produce good-tasting oranges or mandarins with as much hardiness as possible without poluting it with P. trifoliata.  Others are working on this, so I won't be working on it.
Pop 5 is where my energy has been so far.  Half P. trifoliata, half citrus.  I have about 25 Sanford open-pollinated seedlings, and 2 US 852 seedlings.  I have been promiced some open-pollinated C. ichangensis x P. trifoliata seeds. I have some other citranges which I'll be using for pollen, so my gene base will have some diversity. I am working mostly on this population at first because until these bloom, I can't do selection or crossing to make other populations.  Plans are to select only for precocity, monoembryony, cold hardiness, and flavor.
Flavor selection will only be against P. trifoliata  flavor.  It will still be too sour for most people, but until the P. trifoliata flavor is dealt with, lack of sweetness is a minor problem.
Selection for cold tolerance will be done by keeping cuttings in a freezer for a week and see which survive.  Each population will have its own temperature. which will change slightly in each generation.  I'm doing experiments now to see what temperatures I'll be starting with.
Precocity will be easy to detect, I think, as well as monoembryony.  I have read that one (or more) citrus variety makes monebryonic seeeds via appomixis.  I'll have to watch  out for that by checking that seedlings aren't too uniform.
When population 5 blooms, crossing it with populations 1 and 9 will give populations 3 and 7.
If any of population 3 can survive here in zone 6, then populations 1 and 2 will not be needed.  But I'm not counting on that.
If any of population 7 has good fruit, population 8 and 9 won't be needed.  But I'm not counting on that either.  I have been encouraged by  reading of Dr. Brown's work with cold hardy citrus.  Some of his would be like population 7.  But I haven't tasted any of his citrus, so I don't know how accurate the reports are.
Population 7 would be the place for Troyer citrangequat, which some people enjoy.  I read that its seedlings don't do well, and I am not planning to use it.  Comments about this are welcome.
Crossing populations 7 and 9 give pop. 8.  Some of these should be edible, if not really good.  I'm prepared to select for flavor for a several generations.  And selection for cold tolerance for several generations might give measurably more cold tolerance.
Crossing populations 7 and 9 will give pop 8.  I expect some to taste quite good even in the first generation.  Perhaps I'm too optimistic.  We'll see.  Likewise we'll see if 1/8 P. trifoliata will give any increased cold tolerance.
Crossing populations 5 and 7 will give population 6, 3/8 P. trifoliata and 5/8 citrus.  Selections will be as for pop. 5.
Crossing populations 3 and 5 will give population 4.    Selection will be as for pops 5 and 6.  Selections is most effective generally when genes are around 50% frequency.  So pops 4, 5, and 6 will give greatest improvement.  Pops 7, 8, and 9 will give good fruit sooner though and somewhat increase the range of good citrus.
Crossing pops 1 and 3 will give pop 2.  If pop 3 gives any winter-hardy seedlings, pop 2 will never exist.  And pop1 would be dropped.
I plan to grow out at least 200 plants per population per generation.  More would be better, of course, but space is limited.
Populations will be dropped, or better still, turned over to other people when they have served my purpose, or better still, as someone else sees their potential and wants to take them on.
Monoembryony should quit being an issue in 3 or 4 generations.
Precocity is very important and will always be selected for, but there will be a limit.
Flavor and winter-hardiness will need work longer than I expect to live, and I expect to live a long time.  That is why I'm hoping others with the means will take an interest in this.

I know that cold tolerance alone doesn't give winter hardiness.  A winter-hardy plant must become cold tolerant before the first hard freeze of winter, and maintain cold tolerance in spite of mid-winter warm spells.  But the lower number populations should include winter survivers because they are mostly P. trifoliata, which survives well here.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 18, 2017, 05:45:04 PM
From what I know precocious flowering gene in poncirus is recessive , you need two copies of it to express this feature.
There exist "edible" poncirus clones like Swamp Lemon and Poncirus+ that could be  better starting points at  your pop1 level to produce further F1 populations.
Another comment- since your breeding goal is hardiness for z6, you necessary should select for deciduous trait, even in your pop 5 population crossings.   
Title: Re: Long term cold hardy citrus breeding project
Post by: Farmerche on December 18, 2017, 05:58:30 PM
Towards the goal of starting with more desirable poncirus, I can offer my flying dragon variety which originated as a seedling. It is very resilient and has a sour but not bitter, slightly floral taste. It is small and seedy though. I'm am actually beginning my own effort at breeding with it in which I hope to stick mainly to poncirus but maintain this seedlings flavor but get to a larger less seedy fruit.
If you are interested in cuttings from my variety in spring let me know.
Have you looked at the earliest fruiting mandarins for crossing efforts. This could be important for controlling for dormancy.
Title: Re: Long term cold hardy citrus breeding project
Post by: Isaac-1 on December 18, 2017, 06:08:02 PM
Thanks for posting this somewhat detailed plan, I hope you keep us updated as it  progresses.    My one suggestion is that you actively work to find someone in your region to collaborate with.   All too often these sorts of long term individual projects get side track by unexpected life events of the originator. 
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on December 18, 2017, 06:45:23 PM
I'm also breeding cold-hardy citrus, but I'm focusing more on things that could survive in zone 8.

I believe zone 8 is pushing it, but still within the reasonable range of what something good tasting could grow in.

As for cold hardiness testing, my plan is just to breed everything to two generations and then, out of all the offspring, see which ones can survive. That's the fastest way to accelerate things. I'm also planning to propagate a clone of each sample before it undergoes testing for cold hardiness, that way if it survives the cutting will have been already growing the entire time, so there won't be any Winter setbacks in the breeding process. The drawback to this approach is having to grow more cultivars without knowing whether they're going to be cold-hardy.

If I can make a suggestion for you, zone 6 is going to be really difficult. You might try to make a backcross that contains more than 50% poncirus in its ancestry.
Something like this:
 ([citrumelo x mandarin] x poncirus) x (citrange x poncirus)
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 01:03:11 PM
Thank you all for your useful replies.
Ilya11, I agree that the precocious trait is recessive.  But it is worth the wait since this a long term project. 
I didn't know about Swamp lemon and Poncirrus+.  Do you know where I can get them? I'll google as soon as I get done with this post.   It sounds like they would be worth having even if I wasn't breeding.  Any idea of the inheritance of the edible trait?
I agree that most of my work will be with deciduous stock.  Even the deciduous trees mostly won't be hardy here.  Evergreen trees are out of the question, except protected as breeding stock.

Farmche.  I am quite interested in your Flying Dragon seedling.  I am suprized at an edible fruit from that source.  Cutting and/or seed would be very usefull

Isaac-11.  I am looking for collaborators.  I expect this to take 30 years if I am very lucky.  Likely it will take longer.  And I am 67 years old.  So if I don't get collaborators,  I am only amusing myself, not really doing useful work.

SoCal2warm.  I'll be keeping a clone of each seedling to fruiting.  I'll want to cross the most cold hardy with the best fruit in each population in each generation.  My plan is to intercross the 10 best trees in each population in each generation.
As for your suggestion to backcross the F1 trees to P. trifoliata, that would be population 3 above.  Actually, I plan to make a second backcross to P. trifoliata if necessary.  That would be population 2.

So is anyone crossing Swamp Lemon, Poncirus+ or the Flying Dragon seedling with quality citrus or kumquats?  If not, times being wasted.   
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 01:07:16 PM
I read a paper written way back that said the Citrus x  P. trifoliata F2 is less winter hardy than the F1., and that hardiness is less in each generration.
I think I know the explanation. 
In the  F1, all the genes for winter hardiness are there, but only one copy of each.  We all knew that.
In the F2, 25% of those genes are there with 2 copies.  Good.  And 50% of the genes are there with single copies like the F1.  No further loss there from the F1.  But 25% of the genes for winter hardiness are not in a given F2 plant.  And in the F3 25% of the genes  hetrozygous in the F2 are gone, and so one.
It is not just that genes are being lost, the genes have co-evolved and some of the genes remaining won't work well without the genes that are gone. 
If I just worked selecting in the F2, F3, F4, etc., selection won't be effective on those genes that require those genes that are missing.  So selecting only in population 5 won't be effectively selecting for all genes involved in winter hardiness.  Only as some of the genes that have some effect alone are selected will the others start becoming effective and be acted on by selection.
That is why I'll backcross the F1 to P. trifoliata, to have more of the hardiness genes present.  This will allow selection to work on those genes that need other genes to interact with.  A second backcross, Pop 2, may be needed to get the majority of genes available for selections.  That remains to be seen

In the same way,  flavor is the result of many genes interacting.  Population 8 will at first only be able to use cold hardy genes that have significant effect without all those other genes which will be missing,  But it will have all the genes necessary for good flavor, plus some genes for bad flavor which will be discarded.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 01:22:33 PM
Farmche.  You mentioned early fruiting mandarins.  I haven't looked into them.  I should.
So far, I have been collecting and growing only pre-existing poncirus hybrids so I could get on with the breeding.  I plan to aquire Clementine this spring as it makes sexual seeds.  I realize that a problem I'm not addressing yet is the short season here. 
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 19, 2017, 02:39:45 PM
Walt,
Both Swamp Lemon and Poncirus+ were described on defunct CitrusGrowers forum.
Below is an extract of this discussion presented by Sylvain on the AgrumesPassion French forum
http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic5861.html (http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic5861.html)

Poncirus+ have essentially no internal sticky oils and it seems that its seeds contain a single embryo.
On the left is  juice of the regular poncirus, on the right that of Poncirus+
(http://s019.radikal.ru/i641/1712/50/3c753767dcbc.jpg) (http://radikal.ru)

Next spring I am planning  to cross them in  a hope of obtaining even better quality of fruits.
I shall be glad to provide you  hybrid seeds, if you are interested.

I am not fully agree with your reasoning for rejection of of the progeny of direct hybrids between poncirus and edible citrus.
Of course, if you consider all the plants in F2, F3 and so on generations, they become more and more heterogeneous in respect of the presence of genes for hardiness, but due to the chromosome crossing-overs the two genomes will be progressively  present in the smaller and smaller intermingled fragments finally resulting in the separation of genes for bad the quality of poncirus fruits from the genes of hardiness in particular plants. This will be less possible in your pop3 and pop2 populations.

If you select for extreme hardiness ( comparable to that of poncirus ) in each subsequent generation of intercrossing inside pop5 population, and simultaneously keep selection for better and better  hardiness, discarding the rest, you will produce hardy plants with higher and higher proportion of edible citrus genome.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on December 19, 2017, 02:42:34 PM
Walt, I'll collaborate with you.

It's true I have no interest in something that is mostly trifoliate in its ancestry, but maybe I can use what you develop to hybridize something and you can take what I develop and cross that with trifoliate.

If I can make a suggestion, you should consider using an indoor grow tent to accelerate growth. I believe it's possible to go from seed to fruit in as little as 3 to 4 years if the temperature is constantly kept above 75 degrees and the humidity is contained (and the potting soil is kept consistently watered, makes sure the plant containers allow plenty of root space as well). You may be able to find a grow tent on the internet for under $45 (2.5 x 2.5 ft or 2 x 4 ft seem to be economical sizes). I usually use incandescent/halogen bulbs inside during the Winter, and have one tent with a little 250W heater on a thermostat temperature control outlet. (I put a gallon container of water right in front of where the heater blows to help keep the temperature moderated, and block the path of dry air to help avoid it causing any of the plants to get dried out)

I hope to breed something that is going to be supermarket quality in taste but survives without much trouble in a zone 8 climate (not just zone 8 but a cool zone 8 climate where the period of summer heat is not that long). This could be pretty useful to someone trying to breed cold hardier citrus because you would already having something that could survive a fair level of cold and tastes good, so it would be a shorter jump for you to get something with extreme cold tolerance that tastes acceptable.

Anyway, hope to stay in touch over the next few years.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on December 19, 2017, 03:09:27 PM
I agree with you about those recessive genes, Walt.
Something I've been thinking of, you might try making crosses between hybrids that are 50% trifoliate and hybrids that are 25% trifoliate, hoping that some of the recessive genes were retained in the 25% hybrid. If you do crosses with enough different hybrids, you're bound to eventually get something that expresses the full (or closely so) trifoliate cold hardiness phenotype even though it's slightly less than 50% trifoliate in its ancestry.

I know someone who breeds reptiles and he often has to resort to second generation backcrossing to obtain offspring that express recessive traits.

Another thing to be aware of is that some citrus varieties produce more nucellar seeds than other varieties. (nucellar = true to seed, genetic clones)
So if you're making a cross, you might select a variety more likely to produce zygotic seeds as the female parent, and then grow those seeds. Citranges only rarely produce zygotic seeds, so not a good choice for the female parent. In some cases you might just have to grow the seeds to full plants without knowing whether they were true to seed yet.
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on December 19, 2017, 03:11:20 PM
Ilya11, could you please explain what is a poncirus+.  I am not familiar with that term.  Thanks.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 03:49:38 PM
Poncirus+ is new to me too.  And google doesn't have anything on it.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 04:10:27 PM
SoCal2warm.  I am aware of the nucellar seedlings.  I am using seedlings of Sandford citramagee. which is said to be completely zygotic, and US 852 citandarin which is said to be 50% zygotic.
I have about 25 seedlings of an open pollinated pure P. trifoliata that has zygotic seeds.
The 50% zygotic citandarin is the most nucellar seed source I plan on using.  I have decided to use use pollen fromcitandarins and citranges that are nucellar for a couple of generations because I don't want to limit the genetic diversity.  But I will be limiting use of non-zygotic plants after that.
I have a 200 sq. ft. greenhouse.  That is a little less than 20 sq. meters.  I plan on building more.  In spite of the cold spells we get here, it is sunny enough that I have overwintered tomatoes in sunken unheated greenhouses.  I plan to build more.
I am investigating venting my hot water heater into my greenhouse to add CO2, as well as heat.  I'll be installing a CO monitor too.  Neither I nor my citrus like carbon monoxide.

Yes, stay in touch.  It will be a couple more years before My next generation starting.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 19, 2017, 04:16:58 PM
I agree with you about those recessive genes, Walt.
Something I've been thinking of, you might try making crosses between hybrids that are 50% trifoliate and hybrids that are 25% trifoliate, hoping that some of the recessive genes were retained in the 25% hybrid. If you do crosses with enough different hybrids, you're bound to eventually get something that expresses the full (or closely so) trifoliate cold hardiness phenotype even though it's slightly less than 50% trifoliate in its ancestry.
.

That would be pop 4 in my first post.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 19, 2017, 05:39:40 PM
Poncirus+ is a chance seedling of trifoliata growing near Yalta, Crimea.
It was found by Forward,  the old  member of CitrusGrowers forum. He posted some photos of it on the  Ukrainian citrus forum.

http://citrusforum.org.ua/viewtopic.php?f=57&t=86&start=210 (http://citrusforum.org.ua/viewtopic.php?f=57&t=86&start=210)

Google translation ;D
http://translate.google.com/translate?hl=fr&sl=auto&tl=en&u=http%3A%2F%2Fcitrusforum.org.ua%2Fviewtopic.php%3Ff%3D57%26t%3D86%26start%3D210&sandbox=1 (http://translate.google.com/translate?hl=fr&sl=auto&tl=en&u=http%3A%2F%2Fcitrusforum.org.ua%2Fviewtopic.php%3Ff%3D57%26t%3D86%26start%3D210&sandbox=1)
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on December 19, 2017, 10:18:00 PM
Thanks Ilya11 for the explanation. Seems to me Forward could make a lot of money on Poncirus+.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 20, 2017, 01:21:01 PM
I googled poncirus+ and got nothing.  Thank you Ilya for the information you provided.
I googled Swamp Lemon.  I got only one hit, a blog at

http://hardycitrus.blogspot.com/2017/06/swamp-lemon.html (http://hardycitrus.blogspot.com/2017/06/swamp-lemon.html)

I found no commercial source, but the blog does have a source.
 "only growing wild along the west side of Rte. 74 where it crosses the Livingston Creek. "
That's in North Carolina, USA.  Quite a drive from Kansas, but if no other source is available I might do it.
Who do I know who lives in North Carolina?
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 20, 2017, 01:26:51 PM
I didn't sleep much last night.  The 3 variations on P. trifoliata have me excited, thinking about how they could shorten my breeding plans.  Without the evil flavor of P. trifoliata F1 hybrids, citranges, citandarins, citanything, would be much better.  No substitute for the best southern grown citrus, but enough to thrill me.  Thanks to everyone!
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on December 20, 2017, 03:01:10 PM
There was some talk about using early maturing citrus. The earliest maturing mandarin I know of is the Xie Shan satsuma (which can easily be purchased in the USA).  Xie Shan can mature as early as mid-September
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 20, 2017, 03:06:34 PM
Walt,
Bernhard Voss from Hamburg succeeded to produce a deciduous hybrid between Ichangensis and Poncirus that resist to -21C (USDA zone 6b).
It is listed as  "Neuzüchtung" at his site (http://www.agrumi-voss.de/index.php/anmeldung/frosthaerte-rangliste), also has a name N2tri.
I have it, not flowering yet, but it is shredding all leaves in early November.
Title: Re: Long term cold hardy citrus breeding project
Post by: Citradia on December 20, 2017, 08:32:02 PM
Walt, I looked up Livingston Creek in NC: it's crossing hwy 74 just west of Delco in Columbus county, on the south coast of NC just one county east of Wilmington. I've driven through there several times this year. I'd love to look for swamp lemons over there, but since that's 4.5 hours from where I live, don't know when I'll be able to go out there. My husband's father grew up in Whiteville in Columbus county, and he tells me he used to season fish they caught from local rivers with a small wild citrus that grew there, but he says he didn't call it a lemon.
Title: Re: Long term cold hardy citrus breeding project
Post by: Farmerche on December 20, 2017, 08:37:02 PM
I think two new varieties Iwasaki and Nichinan are slightly earlier than Xie Shan.

Walt I can send you a cutting from my FD now if you think you can work with it but if not we can wait until later in spring.

Any chance we can get poncirus + into the US?
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on December 21, 2017, 02:05:13 AM
Walt, I looked up Livingston Creek in NC: it's crossing hwy 74 just west of Delco in Columbus county, on the south coast of NC just one county east of Wilmington. I've driven through there several times this year. I'd love to look for swamp lemons over there, but since that's 4.5 hours from where I live, don't know when I'll be able to go out there. My husband's father grew up in Whiteville in Columbus county, and he tells me he used to season fish they caught from local rivers with a small wild citrus that grew there, but he says he didn't call it a lemon.

hardyvermont did some research. He might know the place... I think he is on this forum too.
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on December 21, 2017, 10:20:14 AM
Farmerche, getting permission to import poncirus+ into the USA, would have to go through the USDA, and that would be a BIG BIG BIG nightmare.  Especially with all the present citrus problems going on in this country.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 21, 2017, 10:46:17 AM
Millet,
The seeds, are they also restricted?
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on December 21, 2017, 11:02:46 AM
Llya11, no I think seeds would be OK.  I have sent seeds of various citrus cultivars to Europe and Asia, and by the time they arrived 60 percent  were dead or damaged.   I assume that poncirus+ is as slow growing as regular poncirus, therefore how many years do you think it would take from germination to fruiting.?
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on December 21, 2017, 11:46:23 AM
seed import is forbidden by the EU since about 1 year.
Title: Re: Long term cold hardy citrus breeding project
Post by: starch on December 21, 2017, 12:00:24 PM
Walt,

This is an ambitious and exciting project. Thank you for sharing it with us!

I have family in Middle Tennessee (Zone 7a) and they all love citrus. And years ago I used to ship them citrus that I grew on my trees. But now with the psyllid and the quarantine on citrus, I can't send them citrus from my yard in AZ anymore. But I would love for them to be able to grow some of their own citrus.

I have one family member in TN who is a little more enthusiastic about growing plants and I think he would be very interested in being part of your trial process.

Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on December 21, 2017, 12:23:16 PM
Llya11, no I think seeds would be OK.  I have sent seeds of various citrus cultivars to Europe and Asia, and by the time they arrived 60 percent  were dead or damaged.   I assume that poncirus+ is as slow growing as regular poncirus, therefore how many years do you think it would take from germination to fruiting.?
Of course it depends on conditions, when grown in the winter under the lamps for two years and then planted outside I observe that most of the poncirus seedlings flower in 5-7 years.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 21, 2017, 12:39:36 PM
There was some talk about using early maturing citrus. The earliest maturing mandarin I know of is the Xie Shan satsuma (which can easily be purchased in the USA).  Xie Shan can mature as early as mid-September

Mid September would be very good here.  Most would have to ripen inside even if they were winter-hardy.  I have assumed that early ripening genes would come from P. trifoliata as they ripen here.  But they don't ripen sweet.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 21, 2017, 12:44:33 PM
Walt, I looked up Livingston Creek in NC: it's crossing hwy 74 just west of Delco in Columbus county, on the south coast of NC just one county east of Wilmington. I've driven through there several times this year. I'd love to look for swamp lemons over there, but since that's 4.5 hours from where I live, don't know when I'll be able to go out there. My husband's father grew up in Whiteville in Columbus county, and he tells me he used to season fish they caught from local rivers with a small wild citrus that grew there, but he says he didn't call it a lemon.

Thank you.  Any lead is useful.  I'd certainly help with gas money.  I don't know about you, but I wouldn't recognize P. trifoliata during the winter.  So there is time for planning.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 21, 2017, 12:54:50 PM
I think two new varieties Iwasaki and Nichinan are slightly earlier than Xie Shan.

Walt I can send you a cutting from my FD now if you think you can work with it but if not we can wait until later in spring.

Any chance we can get poncirus + into the US?

Thanks for the information about early ripening mandarins.  Ill be trying all three that have been recommended. 
About the FD cutting, my P. trifoliata that are big enough for me to graft are all outsice and dormant.  I do have 3 citranges that are inside and big enough to graft are just surviving due to not enough light.  I like to graft onto rapidly growing stocks so they heal fast, before the scion dries out.
I have grafted apples in late spring with dormant scions onto leafed out stocks.  I assume that would be best for citrus, right?
Title: Re: Long term cold hardy citrus breeding project
Post by: Citradia on December 22, 2017, 06:44:05 PM
Walt, I do know what PT looks like in winter and some brightly colored fruits may still be in branches, so I'd like to try to find the trees you spoke of. I also intend to call some of Whiteville's nurseries to see if they may already have some of their local PT for sale. I'd drive 4 hours on a weekend to get my hands on a better quality hardy citrus. I need to wait until after the holidays though.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 28, 2017, 02:25:24 PM
I want everyone to know that, while i have read read about citrus from many sources, most of what I know I learned from the now gone citrus forum, whose name I don't remember.  But I do see many names here that I recognize, people who I highly respect, from that forum.  It good to have such experts taking this project seriously.
Title: Re: Long term cold hardy citrus breeding project
Post by: Tom on December 28, 2017, 10:10:01 PM
I think the old forum was  citrusforumup.com  it is long gone but there are efforts being made to resurrect it or at least try to make the archives accessible. It was owned and operated by Laaz and he had several administrative assistants [including Millet who started this site] but he called them something else. Seems that nobody’s heard from Laaz lately.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on December 29, 2017, 04:13:19 PM
That's the one.
Title: Re: Long term cold hardy citrus breeding project
Post by: Zitrusgaertner on February 13, 2018, 08:01:22 AM
Millet,
but it should be possible to send seed from Europe, or not? The other way it was no problem. USDA sent me a lot of seeds years ago. Without charging anything very nice!
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on February 13, 2018, 12:43:51 PM
Zitrusgaertner, I'm not sure on European regulations, perhaps someone living in the EU can answer your question.  I know in the USA seeds can be sent anywhere.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on February 13, 2018, 01:09:34 PM
I believe European regulations concern only plant material send to EU, not vice versa.
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on February 13, 2018, 02:42:50 PM
It is a mess with these regulations.
I owe an official paper saying I am allowed to import Citrus seeds. But USDA and NIAS are claiming EU regulations prohibit seed import.
At least I am ready to accept that foreign officials understand EU regulatzion better than german offcials do.
Both are referring to the same regulations :(
Title: Re: Long term cold hardy citrus breeding project
Post by: Zitrusgaertner on February 15, 2018, 08:31:36 AM
Mikkel

There is an old proverb saying: He who asks a lot of people will loose his direction (auf Deutsch: Wer lang fragt, geht weit irr). Sending citrus seed to a private person will not bring you in jail. And deseases are not transferred via seed as far as I know.
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on February 16, 2018, 05:02:20 PM
I am not concerned about jail but I am interested in getting seeds. The hard fact is UCR and others refuse to send them because of this regulations :( 
Title: Re: Long term cold hardy citrus breeding project
Post by: Zitrusgaertner on February 17, 2018, 03:48:18 PM
Mikkel, don't you have a friend in the US who could order and send on the seeds to you?
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on February 23, 2018, 03:35:46 PM
 ::) ich bin unschuldig... English = I am innocent
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 09, 2018, 04:40:44 PM
Does citrus pollen store well and ship well?
I ask because I am impatient to get some crosses made and hybrid seeds started.  Breeding trees takes patience, and I'd be OK with that if I had no other options. 
But I know there are people here who have mature plants of some I've been growing on, and might make some pollinations if they had pollen.  and there may be people with mature plants who might donate pollen.  Yes?
When I started this thread, I was thinking in long term plans.  But since there are mature plants of non-disgusting P. trifoliata, and US 852, for example, such a cross might be made this spring and we'd be that much closer to having something edible and more hardy than now exists.
But first step is to see if it is possible.
I realize that P. trifoliata blooms earlier than citranges or citanderins, etc.  So it might not work making the cross in the direction I'd like, unless the P. trifoliata is much further north than the US 852.  Perhaps a  US 852 x citrange?
Anyone have information or ideas?
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 10, 2018, 03:56:11 AM
Depending on weather conditions there is some overlap between poncirus and its hybrids  flowering. Otherwise, pollen can be dried and stored up to one year at -20C in containers with  a small bag of silica gel.
Last year I succeeded in getting citrumelo 5* x  Flying Dragon hybrid seedlings, but it was after several years of failures.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 10, 2018, 12:53:00 PM
This is the first 3/4 P. trifoliata, 1/4 citrus I've heard of.  Any idea of how hardy it will be?  I know, or believe, that the citromelo, being a hybrid will be segregating, so there could be great variation in such hybrids.  I'm willing to go to 7/8 P. trifoliata, 1/8 citrus, but I hope I don't have to.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 10, 2018, 12:56:09 PM
Also 2 other question.
Do you know of other 3/4 P. t., 1/4 citrus?
Did you use a P.t. with their usual flavor or one of the mutants with better flavor?
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 10, 2018, 01:58:02 PM
This is the first 3/4 P. trifoliata, 1/4 citrus I've heard of.  Any idea of how hardy it will be?  I know, or believe, that the citromelo, being a hybrid will be segregating, so there could be great variation in such hybrids.  I'm willing to go to 7/8 P. trifoliata, 1/8 citrus, but I hope I don't have to.
The seedlings currently  are growing under the lamps, the largest is ~20 cm high, they will go in ground in May. Citrumelo 5* is a chance seedling of Swingle citrumelo, most probably from self pollination, it is "nearly edible", more hardy than Swingle and it gives a fair amount of zygotic seedlings.   The hybrids I got now ( with FD) are indeed very heterogeneous , some are pretty strong but most are dwarfs.

Also 2 other question.
Do you know of other 3/4 P. t., 1/4 citrus?
Did you use a P.t. with their usual flavor or one of the mutants with better flavor?
B.Voss in his book on hardy citrus reproduces from "Citrus growing in Florida" book by L.K.Jackson  a scheme where a backcross of citrange by poncirus is named cicitrange, so most probably such hybrids were already made.
 I  have plans to use other strains of poncirus, but it seems it is more difficult than to cross 5* with regular citrus.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 11, 2018, 04:31:57 PM
I am thinking that all the citrange, citandarin, citquat, etc., should be remade using the better tasting P.t.  Also with the more zygotic P.t., and with precocious P.t.  I know that is a lot of work and will take a lot of space.  But I am retired and I have no desire to sit around waiting to die.  And I thought my origonal plan, which I still plan to do, was pretty ambitious.
Title: Re: Long term cold hardy citrus breeding project
Post by: Samodelkin on March 12, 2018, 05:27:20 PM
The taste of the fruits of trifoliata strongly depends on climatic conditions. In a favorable year, with abundant rainfall, the resin is almost there. In a dry cool year Poncirus+ = Poncirus
Title: Re: Long term cold hardy citrus breeding project
Post by: Samodelkin on March 12, 2018, 05:36:11 PM
The taste of the fruit of hybrids Poncirus also influence the level of farming and growing conditions. For example, hybrid Trifeola under favorable conditions, the leaves become solid, if the deterioration of conditions trifoliatum. Trifeola = Poncirus+Mineola, fruit is almost edible
(http://f23.ifotki.info/org/076958fcdff373446f7f43c93859e0b4bcbf14303550327.jpg) (http://i-fotki.info/)
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 13, 2018, 02:01:22 PM
Thank you for the information.  "almost edible" is not my goal, but it is a step along the way.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on March 13, 2018, 09:01:08 PM
The plants will grow much better inside if surrounded by some sort of an enclosure to hold in the humidity and keep the surrounding air from getting dried out.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on March 14, 2018, 12:37:42 PM
Ilya.  How many of the citrumelo 5* x  Flying Dragon hybrid seedlings do you have?  I ask because I plan backcrosses of various 3/4 P.t. 1/4 citrus, and I'd like to know how much segregation for cold tolerance there is in the backcross 1 generation.  I will be following your results with great interest.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 14, 2018, 01:20:03 PM
Ilya.  How many of the citrumelo 5* x  Flying Dragon hybrid seedlings do you have?  I ask because I plan backcrosses of various 3/4 P.t. 1/4 citrus, and I'd like to know how much segregation for cold tolerance there is in the backcross 1 generation.  I will be following your results with great interest.
Last spring I pollinated with FD 20 castrated flowers of 5*, got 6 fruits in autumn, totally with 45 seeds.
It gave 43 seedlings; 12 of them are clear hybrids.
Title: Re: Long term cold hardy citrus breeding project
Post by: Zitrusgaertner on March 14, 2018, 04:28:25 PM
Ilya, are there any crosses with swamp lemon? Is there a chance to get rid of bitterness and resin in F1-hybrids? And: do swamp lemon flowers smell?

Best Regards
Robert
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 14, 2018, 05:17:45 PM
Robert,
Swamp Lemon flowers have no smell, I have not yet seen the flowers of Poncirus+ clone, hope it will flower this spring.
Hope that the absence of oils is a simple hereditary trait that will be transmitted in crosses.
Title: Re: Long term cold hardy citrus breeding project
Post by: Zitrusgaertner on March 16, 2018, 09:26:42 AM
Ilya, are the genes identified that cause bitterness and resin in normal poncirus? If not, would it be possibel to find out if you compared the genome of normal poncirus and swamp lemon? Or do I think too simple? Do you plan to make crosses with swamp lemon?
Questions over questions -sorry. Maybe I am a little too enthusiastic about the possibilities.  ;)

Best Regards
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 16, 2018, 10:48:44 AM
Robert,
I am not aware of any mapping of internal oil trait in poncirus. Certainly, it is not a priority for citrus biology projects both in academia and industry. On the contrary, the genetics of bitterness due to the presence of modified flavonones naringins and neohesperidins is quite well studied in citruses.
One can map the genes responsible for fruit oils by genotyping  the segregating population of normal PTxSwampLemon cross, a comparison between the two parent plants is not sufficient, there will be too many differences that have nothing to do with this trait.
I have plans to cross Poncirus+ that is apparently monoebryonic to SwampLemon  to see if the fruit quality can   be further improved.   
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on March 20, 2018, 11:59:42 PM
Something that I think worthwhile would be to try crossing Dunstan citrumelo with C. ichangensis. Might be hardy to zone 7, in a sunny warm spot.

More long-term, maybe a citrumelo cross with Satsuma mandarin, before being crossed with C. ichangensis.
The first cross is going to be more difficult because 90% of the offspring will grow true to seed.

 (it's a similar zygotic to nucellar ratio for both Satsuma mandarin and Swingle citrumelo, whichever is used as the fruit parent, I just looked it up)

The Swamp Lemon, it sounds like Trifoliate (which has become naturalized and been observed growing wild in some of those areas) might have hybridized with something else. Over a few generations, being spread by birds, the less bitter offspring could have been naturally selected for. Or might even be the zygotic progeny of Swingle citrumelo rootstock. Maybe someone long ago tried planting a grapefruit tree out there and it died down to its rootstock over the Winter, then later fruited and the seeds got thrown into the ground and sprouted. Long ago the first grapefruits were rather small and grew in clusters on the branch like grapes, so it might have simply just reverted back to a smaller fruit size. That's what one would expect if they were propagating out in the wild.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on March 21, 2018, 05:06:13 AM
I do have many hybrid seedlings of crosses between citrumelo ( 5*) with Miyagawa and two different clones of ichangensis.
Title: Re: Long term cold hardy citrus breeding project
Post by: ethane on April 09, 2018, 04:24:14 PM
Hi Walt and everyone,
I would love to be able to help on this project, as I have some experience with breeding citrus. My PhD dissertation was on breeding pummelo (Citrus maxima), but I also worked breeding other Citrus. I made a ton of hybrids with Australian Citrus species, which are under evaluation currently at University of Florida. I also made a few hybrids between C. ichangensis and Poncirus trifoliata, which are also at University of Florida. Essentially, all the cool stuff I made are still at University of Florida. Breeding for cold tolerance was not high on our list, as Florida tends to stay pretty warm, and often some tolerance from the rootstock was enough for the tree to survive the occasional cold periods.
It's difficult select purely for cold tolerance, as different factors can affect the tolerance of a particular plant, but recurrent selection using Poncirus with near edible fruit sounds like a good start. I have a some seeds I just started that came from a tree that was 1/4 Poncirus (probably, it makes large, mostly edible fruit and has trifoliate leaves), which I will gladly share material of when I have some to share (legally, of course).
I would also put precocity high on the list; there are some good sources that I would start with. I heard mention of a precocious Poncirus, which is great, but also I would recommend finger limes or desert limes as I know those often flower in a year from seed. So does Fortunella polyandra, but it's fruits aren't so great. Citrus wakonai would also be good if we could get our hands on it.

Below is a picture of a Citrus (Microcitrus) australasica x Poncirus trifoliata hybrid I made at University of Florida.
(https://s7.postimg.cc/tz3jz3f4n/36380540764_256620326f_o.png) (https://postimg.cc/image/tz3jz3f4n/)

Cheers,
Dr. Ethan Nielsen
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on April 09, 2018, 05:04:24 PM
Welcome Ethane.
I'm in the process of re-writing my goal and method because of the responses I got here.  I now have much higher expectations.
I'm now wanting to combine low poncirin and precocious with high percent  monozygotic seeds.
In the meantime, producing 3/4 P. trifoliata 1/4 citrus seedlings to see how much segregation there is for cold tolerance.  Of course that means finding a replicatible way to measure cold tolerance.
We are both in zone 6.  That doesn't mean what works for one of us will necessarily work for the other.  There are so many other factors not covered by a single number.  But more people working on this can only improve our chances.
Walt
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on April 09, 2018, 10:33:51 PM
For zone 6 I'm thinking you are probably going to have to think about combining multiple strategies, not just hybridization, if you want something very edible.
You might, for example, be able to breed something that can survive outside in a warm spot, up against a south facing wall, near water and large rocks to help reflect/absorb/retain heat, sheltered from wind, etc. (basically going out of your way to create a warm microclimate) and possibly covered with insulation during the Winter on top of that. It is possible, but I don't think it's going to be so simple.

One advantage, in Kansas you have clear skies so that means availability of direct sunlight throughout the Winter. That makes it easy to manipulate this sunlight through the use of microclimate techniques to warm the surroundings.

Normal citrus wouldn't be able to survive in this situation, but much more cold hardy varieties may.
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on April 10, 2018, 02:02:28 AM

I would love to be able to help on this project,
That is great! Welcome! I just have some questions I can`t wait to ask :)
I also made a few hybrids between C. ichangensis and Poncirus trifoliata,

Could you report more about these hybrids? Are fruits more likely to be edible than other Poncirus hybrids?
 
I would also put precocity high on the list; there are some good sources that I would start with. I heard mention of a precocious Poncirus, which is great, but also I would recommend finger limes or desert limes as I know those often flower in a year from seed.

I just have different types of "Microcitrus" seedlings in my greenhouse to find out how precocious they are. Do you know if this trait is herited to further generations?
Below is a picture of a Citrus (Microcitrus) australasica x Poncirus trifoliata hybrid I made at University of Florida.

Have you seen fruits of such hybrids in your work? Are they in tendency inedible like the most of Poncirus hybrids?

(https://s7.postimg.cc/tz3jz3f4n/36380540764_256620326f_o.png) (https://postimg.cc/image/tz3jz3f4n/)

Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on April 10, 2018, 03:23:51 AM

(Dunstan citrumelo x Satsuma mandarin) x (Ichang papeda x Satsuma mandarin)

(trifoliate x Satsuma mandarin) x Orange Frost mandarin

(trifoliate x Bloomsweet) x ((yuzu x tangelo) x Changsha mandarin)

((trifoliate x mandarin) x Orange Frost mandarin) x ((trifoliate x pomelo) x Ichang lemon)


Title: Re: Long term cold hardy citrus breeding project
Post by: ethane on April 11, 2018, 06:58:39 PM
Hi Mikkel,
A lot of my hybrids were small plants when I left, so I can't report on their edibility. I do know the particular strain of C. ichangensis I had was not very edible. I'm sure there are better, more edible examples of the species. So the hybrids I made between C. ichangensis and P. trifoliata will likely be evaluated as rootstocks.
Precocity in Microcitrus hybrids seems to be easily passed on. I made some triploid hybrids that were 1/3 finger lime and 2/3 lime or lemon, that flowered after a year. This was surprising, given that finger lime was in the genetic minority. One I sampled I know was self fruitful in the greenhouse and was seedless, which we were aiming for, but the resiny finger lime flavor was also dominant (We also had limited genetics available for finger limes, as most I used were seedlings from California, and there are probably better tasting selections. I know more are in the process of being imported from Australia. It's a long process of importing and cleaning up for budwood release.) I've grown other seedlings that also flowered when a year old. Finger limes also tend to flower multiple times in the year, not just in spring.
The Microcitrus x Poncirus hybrids were also small when I left, which I made last year, so I can't comment on precocity or fruit quality.
Here's an illustration of Microcitrus hybrids I made from my dissertation: EXPLOITATION OF PUMMELO (CITRUS MAXIMA (BURM.) MERRILL) THROUGH BREEDING, PLOIDY MANIPULATION, AND INTERSTOCKS FOR IMPROVEMENT OF CULTIVATED CITRUS; Ethan Nielsen, University of Florida, December 2017.

(https://s9.postimg.cc/pxq9xw963/Leaves_with_arrows.jpg) (https://postimg.cc/image/pxq9xw963/)
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on April 13, 2018, 03:54:58 PM
At the start of this thread, I said I was using mandarine, orange, and P. trifoliata. 
Mandarin because it is my favorite citrus, it is often zygotic, and it is moderately precocious.
Orange because I had access to OP Sanford seeds, and oranges are much like mandarins.
Trifoliate orange, obviously, because it is winter-hardy in zone 5.  It has no other excuse for being in my garden.

Now, in addition, I plan to start another group using finger lime and precocious P. trifoliata.  The F1 should be somewhat precocious because of the finger lime.  The precocious P. trifoliata is recessive by many reports.  The backcross of (fingerlime x P. trifoliata) to precocious P. trifoliata, I hope will segregate for precocity.  Also it will be segregating for winter-hardiness and traits that go together to give winter hardiness, i.e. dormancy that lasts all winter, low temperature tolerance.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on April 25, 2018, 12:35:11 PM
Last year I succeeded in getting citrumelo 5* x  Flying Dragon hybrid seedlings, but it was after several years of failures.

From reading your posts for several years, I'm sure you know what you are doing and how to do it.  So it sounds to me that maybe Ponciris-Citrus hybrids aren't very fertile.  Is that generally true?  Have people tried enough crosses using Ponciris-Citrus hybrids as parents to know how fertile they are?  I have read of the kumquat x citrange hybrids of course.  And Dr. Brown's hybrids.  Those made me think it was easy, but for all I know they resulted from thousands of attempts.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on April 25, 2018, 01:46:19 PM
Walt,
I guess you are right, hybrids  with poncirus and fortunella are more difficult to obtain than crosses between classic citruses.
The first barrier is the time of flowering: early for poncirus or late for kumquats. This of course can be overcome by pollen storage.
I also observed the influence of climatic conditions, with hot weather during flowering favoring  fecundation. I am doing hybridization under open ground conditions, most likely doing it in protected environment would help.
On a top of this, I believe that due to evolution distance these hybrids are more difficult to obtain. I read an article showing a high frequency of aneuploids ( chromosome number  abnormalities) in hybrids between Fortunella and citruses.
Use the bridging varieties like hybrid kumquats, citranges or citrumelos  could be a way to overcome this type of incompatibility. I found that Kucle kumquat hybrid is very easily pollinated by 5* citrumelo to produce interesting zygotic seedlings.       
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on July 11, 2018, 02:46:15 PM
How tall do P. trifoliata have to be to flower.  I'm asking about both precocious and regular.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on July 11, 2018, 04:19:42 PM
Precocious one starts to flower when about 20 cm tall, but fruiting is delayed, most fruits appear in 3 years, many early flowers are incomplete. At this age the second flowering in summer is giving some fruits, but they do not have a time to mature in the open ground.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on July 12, 2018, 02:39:58 PM
Thank you for the information. 
Am I right in assuming that a scion from a plant that has bloomed, grafted onto a meter tall P.t. seedling, will bloom within a year or two? 
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on July 12, 2018, 04:37:15 PM
Given good conditions it will bloom next spring, but fruit formation will depend on  formation of complete flowers with mature styles.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on July 19, 2018, 07:52:16 PM
Those made me think it was easy, but for all I know they resulted from thousands of attempts.

I think the main barrier, in many citrus types (and this tends to be particularly true for hybrids) is a high percentage of nucellar seeds, which means that the majority of the seeds grown will be genetic clones of their parents. Grapefruits tend to be somewhere around 70-90 percent nucellar, for example.
That means you have to grow all the seedlings and you may not know if any are actually hybrids until much later when they begin producing fruits. Although of course there are several strategies to be able to help identify seedlings that are different from their parents.

For example might be using trifoliate citrange pollen on a grapefruit as the female parent. If any of the seedlings have trifoliate leaves, you know they are citrange-grapefruit hybrids. Or possibly the reverse of that could be possible: If any seedlings from a citrumelo don't have trifoliate leaves than they are probably hybrids of the other pollination parent that has ordinary leaves.


Another topic with more information on which citrus types tend to be nucellar: "Thread for Citrus Breeders"
http://tropicalfruitforum.com/index.php?topic=24518.0 (http://tropicalfruitforum.com/index.php?topic=24518.0)

Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 04, 2018, 11:24:40 AM
((C. ichangensis x Duncan grapefruit) x Satsuma mandarin) x Duncan Citrumelo)

(C. ichangensis x Satsuma) x (Satsuma x trifoliate)

(C. ichangensis x (Satsuma x trifoliate)) x ((Satsuma x trifoliate) x pomelo)

Duncan citrumelo x Bloomsweet

Just some ideas


Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on August 04, 2018, 02:34:24 PM
Are these crosses that exist, or crosses you plan?
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 04, 2018, 03:46:58 PM
I do have some Page mandarin & Shasta Gold seedlings, so it would be interesting to eventually try to do something with that.
Two of the most delicious mandarin varieties, btw.

With the exception of Satsuma of course (but that's just individual personal preference talking).
Kishu produces 100% zygotic seeds and is also a very very good one. Believed to be one of the parents of Satsuma, although it doesn't have anywhere near the cold hardiness of Satsuma. Still, it would be a very easy one to cross. Satsuma produces about 90% nucellar seeds, on the other hand.
Title: Re: Long term cold hardy citrus breeding project
Post by: Millet on August 04, 2018, 10:48:16 PM
Kishu is indeed a good tasting cultivar.  I used to have a kishu tree, but I removed it to plant another cultivar.  The main problem with kishu is that they are a such a very small fruit.  I also have a Page fruit, great for juicing, but it is also a small fruit, but larger than Kishu.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 06, 2018, 01:06:49 AM
The main problem with kishu is that they are a such a very small fruit.
Yes, but it's kind of a novelty. They make up for it by being seedless (if the blossoms were not pollinated) and effortless to peel. Little fruits would be frustrating if it took some effort to peel them, but with Kishu that is definitely not the case.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 06, 2018, 09:56:52 PM
A couple grown from seed:

(https://s22.postimg.cc/m62hgwjd9/20180806_123144.jpg) (https://postimg.cc/image/m62hgwjd9/)
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 17, 2018, 11:42:40 AM
I'm thinking if you try second generation hybrids (F2) you might start seeing some interesting traits of much better edibility and higher cold tolerance appear.
For example citrange x citrange, or citrandarin x citrumelo.

This is because some of the genes for cold hardiness could be recessive, so there would have to be a trifoliate ancestor from both parental lines for these genes to be expressed. In other cases there may be a gene in the normal citrus parent which is dominant and detrimental to cold hardiness, so if using a pure normal citrus in even one parent side, it would be impossible for the immediate offspring to not have the dominant gene.

Doing some very basic math, if there were two of these genes (either beneficial recessive, or detrimental dominant, or just a combination of recessive genes, one for edibility and one for cold hardiness, for example) the probability that both would get expressed in the offspring together (assuming this is only out of the zygotic seeds of course) would be 1/16.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on August 17, 2018, 01:57:44 PM
I wish that were true, that some F2 plants were more winter hardy than the F1.  But I doubt it.  Not that I know of any F2 Ponciris x Citrus.  But I'll give my thinking, as you gave yours.
I assume that P. trifoliata has many genes involved in winter hardiness.  Many are incompletely dominant, as shown by the F1 which are more winter hardy than their citrus parent, but less winter hardy that the Ponciris parent.
I have read in an old publication from government citrus research, that the F2 is less winter hardy than the F1. and that it decreases in later generations. 
Now I don't believe that last statement, about the F3.  I have seen no reports on growing a large F3 generation from a large F2 population.  I would think that at most they selected the best F2 and grew out some F3 plants.  If they selected the F2 for eating quality, then the citrus genes for flavor, etc., would be linked to other citrus genes for less winter hardiness.
Don't forget gene linkage when planning crosses!
I'm am not saying not to do the crosses you have in mind.  They are much like I've planned.  I'm saying not be discouraged if what you have in mind isn't in the F2.  I for one, plan to continue select for cold tolerance and good flavor in Ponciris x Citrus in generation after generation, as long as I live.  I certainly don't want to talk you out of doing what you are doing.  I just think it will take longer than one generation.
I think you are in a milder climate than I am.  I think you can succeed quicker than I can.
Good luck.
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on August 17, 2018, 05:48:06 PM

I am not fully agree with your reasoning for rejection of of the progeny of direct hybrids between poncirus and edible citrus.
Of course, if you consider all the plants in F2, F3 and so on generations, they become more and more heterogeneous in respect of the presence of genes for hardiness, but due to the chromosome crossing-overs the two genomes will be progressively  present in the smaller and smaller intermingled fragments finally resulting in the separation of genes for bad  quality of poncirus fruits from the genes of hardiness in particular plants. This will be less possible in your pop3 and pop2 populations.

If you select for extreme hardiness ( comparable to that of poncirus ) in each subsequent generation of intercrossing inside pop5 population, and simultaneously keep selection for better and better  fruit quality, discarding the rest, you will produce hardy plants with higher and higher proportion of edible citrus genome.
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.
Title: Re: Long term cold hardy citrus breeding project
Post by: starch on August 17, 2018, 07:04:46 PM
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.

Wow, that is an ambitious project and a lot work! I hope some of those pan out for you!
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 17, 2018, 11:10:21 PM
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Ilya, be aware that if citrumelo was the fruit parent, likely 70-90 percent of the seeds are nucellar. You may not necessarily be able to tell which ones are nucellar. If citrange was the fruit parent, the percent will be even higher (probably above 98-99 percent).

Unfortunately, that means a lot of the seeds you have may not be second generation hybrids. That means you'll have to wait to find out, if it shows more cold hardiness or better fruit quality than either of the parents (or even if the fruit just looks different).

What perhaps should have been done was to breed a monofoliate hybrid with trifoliate leaf citrumelo, and then identify the seedlings from the citrumelo which are monofoliate (since they must be hybrids).
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on August 18, 2018, 03:43:15 AM
SoCal2warm, beware  that 5star citrumelo when castrated and cross-polinated is giving more than 90% of zygotic seeds and rare nucellar seedlings can be  readily identified.

Before making such remarks as "Beware that ..." you have to acquire your own solid experience in citrus growing and hybridization. (just a friendly advice) >:(
Title: Re: Long term cold hardy citrus breeding project
Post by: Ilya11 on August 18, 2018, 03:52:31 AM
Wow, that is an ambitious project and a lot work! I hope some of those pan out for you!

Yes, I find that  it now looks like a full time job, but luckily  I am retired :)

I still believe , that current number of seedlings is not sufficiently high.
I read somewhere that even when crosses are made between two high quality citrus varieties you need at least 200 hybrids to select something new and valuable.
Title: Re: Long term cold hardy citrus breeding project
Post by: Radoslav on August 18, 2018, 09:45:20 AM
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.

I have a strong feeling, that they are linked to each other. My opinion is that nasty poncirus oil is someting like antifreeze liquid fot the car radiator.
But time will tell .
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on August 18, 2018, 12:40:28 PM
I still believe , that current number of seedlings is not sufficiently high.
I read somewhere that even when crosses are made between two high quality citrus varieties you need at least 200 hybrids to select something new and valuable.
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Most citrus breeders aren't using P. trifoliata as a grandparent.  While larger population is better, I would expect some of your seedlings will not have the Ponciris flavor, mot even a little.  That would be an improvement right there.
Look at Dr. Brown's work.  His populations were about 10% of yours.  But he is said to have had improvement over what was available.  Of course, I don't know first hand.  But I find it encouraging.
That said, I working toward populations of about 200. but so far I have mostly populations of zero.  So you are way ahead of me.
Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on August 19, 2018, 03:10:09 PM
SoCal2Warm.
Ilya wrote that he had discarded all seedlings with the leaf smell of P. trifoliata.  I think that got rid of all nucellar seedlings and left only zygotic seedlings.
I think he also got rid of some zygotic seedlings, as not all zygotic seedlings would lack that smell.  But while the discarded zygotic seedlings might have some good traits, one does have to set standards and stay with them unless something unexpected turns up.  Space is always limited.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 19, 2018, 04:47:54 PM
Yes, leaf smell is interesting. Ichang papeda doesn't have the same leaf smell as Yuzu. Ichang papeda leaves smell very mild and slightly lemony, Yuzu leaves smell more intense and spicy. The difference is obvious, despite the fact Yuzu is believed to have descended from Ichang papeda.
Title: Re: Long term cold hardy citrus breeding project
Post by: Sylvain on August 20, 2018, 06:37:58 AM
> Yuzu is believed to have descended from Ichang papeda.
It is not believed anymore.
Title: Re: Long term cold hardy citrus breeding project
Post by: mikkel on August 21, 2018, 09:05:55 AM
populations size is what me makes think about the most. I am just in the beginning of everything and did only my first small scale hybridisations. That is fine for the start but I know that I need (and want) more seedlings to do selection.

I see 2 main issues in practical work. In the south it would be easier to produce large amount of seedlings but you have to wait for the chance of frost tests. That means you keep more seedlings as you need. (fortunately not my position  ::) )
In the north (like me) it is much more difficult to produce enough seedlings for frost tests. Due to limited space in greenhouse etc. Most seedlings grow very slowly in their 1st season here in our climate. So it is probably better to do frost tests in the 2nd season but that is a matter of space. Small seedlings will be killed for sure whether potentially hardy or not. Too small is too small :(
So it is even much more unlikely to find a hardy one among the small number of seedlings. To talk about edibility is a whole other thing...

I was thinking about a garden in the south, dreaming of Ventimiglia, Italy were I once lived for a short time, but that is far from reality for me. Theoretically it would make it possible for me to produce a lot of seedlings  without to worry about the winter and do large scale frost tests here in the north.
I am still thinking about this possibilty but it only will come in reach in far far future. Now I barely manage to handle my 2nd home and work 160km from here.

Still only spinning around but I keep thinking about that. Especially about how to handle it now...not in future.

Title: Re: Long term cold hardy citrus breeding project
Post by: Walt on August 21, 2018, 03:27:54 PM
My plans are to aim at growing 200 per generation.  They will spend their first summer outside, in pots, then their first winter in the greenhouse.  Outside again for their second summer, then back into the greenhouse, but take cuttings which will be labeled, then packed in moist sawdust, then put in a freezer set at a temperature to be determined later, but the temperature chosen to kill some but not all of the cuttings.  Then the cuttings will be grafted back onto their origional plants to see if they survived.  Or perhaps I'll try to root the cuttings, or maybe I'll learn to identify freeze damage just by look or feel.  I am open to everyone's ideas.  Most of you have much more experience than me.
I do see problems with my plan.  Weather before taking the cuttings will determine degree of hardening off.  And different genotypes will respond differently to the hardening off.  I'm studying work done in apple breeding for ways to select for winter hardiness.  Again your ideas are welcome.

I will also be selecting for % zygotic seeds, precocity, and flavor, so I plan to keep most of the seedlings to bloom, or at least for a few years and then dump those that haven't bloomed.
I expect to build an additional greenhouse each year for 4 years.  I expect to start a new crop of seeds each year, 200 per year. 
Now, if my breeding stock would just bloom already.
Title: Re: Long term cold hardy citrus breeding project
Post by: SoCal2warm on August 22, 2018, 01:14:13 PM
I see 2 main issues in practical work. In the south it would be easier to produce large amount of seedlings but you have to wait for the chance of frost tests. That means you keep more seedlings as you need. (fortunately not my position  ::) )
In the north (like me) it is much more difficult to produce enough seedlings for frost tests. Due to limited space in greenhouse etc. Most seedlings grow very slowly in their 1st season here in our climate.
That's why it is probably more pragmatic to have two different people living in different locations collaborate. One would be in a position to grow out the plants, the other would be in a better position to test them.
This just involves some coordination between different breeders, and exchange of seeds/scions.