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Messages - kumin

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It's good to see flowering and fruiting trees, in contrast to beat up seedlings in recovery!

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

 Waiting until these stems are mature enough to use as scions.

TaiTri seedlings growing nicely.

Citrumelos coming along well.

Surprise Magnolia grandiflora discovered growing under Poncirus. The first seedling in 22 years! 

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: Any opinions.....
« on: May 14, 2019, 07:59:39 PM »
I recall an article about dormant season budding of pome fruit rootstock in which the bareroot rootstock was kept dormant in cool temperatures, while the budded area on the rootstock was maintained at a warm temperature. This allowed the bud to unite with the rootstock in a season which would otherwise have been unproductive.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: May 12, 2019, 06:20:37 PM »
Great idea, Ilya, Poncirus has plenty of acidity to contribute to it's progeny.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: Root graft transferred cold hariness effect
« on: May 09, 2019, 03:54:17 PM »
Socal, yes I attempted to separate one of them and they were fused. I would have needed to break them apart to separate them. I doubt there's much practical application for this. If fact, I suspect that the  opposite is true.  Any root borne disease could quickly and easily pass from tree to tree. I believe this occurs with Red Oaks in the US with the transmission of oak wilt disease.

After reading Ilya's material I see there can be benefits among some species in certain environments.

Cold Hardy Citrus / Root graft transferred cold hardiness effect
« on: May 09, 2019, 01:00:06 PM »
As I'm potting F2 Citrange winter survivors I'm noticing an interesting phenomenon. Due to the large number that were hand planted (20,000 - 21,000) plants, they were planted 4 per hole. Even so, planting took 40 hours to complete.

I've noticed some of the hardy plants have one or more of the companion plants beginning to grow from a low point on the stem. As I attempt to separate them, some are joined by self-grafted roots. It appears the hardy plant has slightly increased the hardiness of the joined companion plant. The stem of the recipient plant has only slightly increased stem hardiness. The effect is noticeable very low on the stem, just above the roots. It appears planting them individually would have prevented this, however 40 hours of hand planting was near my endurance limit.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: Some rare variety hardy seedlings
« on: May 07, 2019, 04:41:05 AM »
Variation is to be expected in zygotic F2 populations. It's an expression of the recombination of the genetic material in the F1 hybrids. Resessive traits that were not expressed in the F1 can now be expressed. An example would be F1 trifoliate plants producing F2 unifoliate progeny.

Cold Hardy Citrus / Re: Talking to G the other day...
« on: May 05, 2019, 03:37:30 PM »
Almost a bonsai with minimal effort.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: Citrumelo 5star in full bloom
« on: May 05, 2019, 10:29:11 AM »
Outstanding plant, how old is this plant?

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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

A unique plant that had zero dieback, not especially vigorous (small leaves). This plant was clearly taller than the snow cover.

2 fairly vigorous specimens.

The large pots are F2 hybrids potted in March, the remainder are 2019 seedlings of several cold hardy selections.

A vigorous F2 unprotected specimen.

2 additional specimens.

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.

Cold Hardy Citrus / Re: Poncirus seed
« on: April 27, 2019, 04:06:32 AM »
Poncirus branches vary in degree of thorniness, by position on the tree. Vigorous growth can have thorns at least 4" in length. Mature fruiting branches in higher position within the tree have greatly reduced thorns, approaching near absence.
Seeds from a nearly thornless fruiting branch that has very thorny juvenile branches elsewhere on the tree can't be expected to genetically transmit thornlessness to it's progeny.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

Cold Hardy Citrus / Re: Some rare variety hardy seedlings
« on: April 25, 2019, 07:05:40 AM »
Referring to rooting cuttings, the goal is to provide a relatively cool humid environment for the upper stem and foliage, while providing heat to the buried lower stem, so as to allow the energy reserves in the cutting to be directed to root formation rather than new foliage formation. When a plant has top growth removed, it directs it's effort toward restoring the balance by sending out vigorous new shoots. Likewise, it's important to assist the plant in it's natural attempt to replace the balance between roots and foliage when the cutting is severed from the mother plant. Only when this balance has been restored should the plant be encouraged to send out new foliage. Almost all horticultural activities function more smoothly when done in concert with the plants natural processes.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« 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.

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