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Messages - kumin

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Cold Hardy Citrus / Re: Zygotic Poncirus hybrids
« on: January 25, 2023, 04:40:34 PM »
I would expect Flying Dragon flowers being pollinated by regular Poncirus to have a fewer Flying Dragon seedlings.

Cold Hardy Citrus / Re: Zygotic Poncirus hybrids
« on: January 25, 2023, 10:06:16 AM »
Were regular Poncirus trees blooming nearby?

Cold Hardy Citrus / Re: Precocity and tree caliper
« on: January 23, 2023, 05:16:52 PM »
I've recently seen suggestions that cold temperatures that aren't lethal may contribute to initiation of phase change. Summer temperatures get rather high, as only the polyfilm ends are removed. As the interior has filled up with growth, ventilation has been reduced. I use cooling misters on the hottest days.
Possibly, both temperature extremes have an effect on maturation, but I don't have any data to support the idea.

Cold Hardy Citrus / Precocity and tree caliper
« on: January 21, 2023, 03:44:41 PM »
Genetics is an obvious factor involved in determining first flowering and fruiting of seedling trees. Another likely factor is the amount of resources the seedling has to utilize to establish trunk stiffening and thickening in order to brace against wind stresses. Trees secured against framework such as trellises and espaliers don't need to allocate as many resources towards trunk and limb framework. Seedlings within an enclosure with a poly or glass skin are also free to transition more quickly to a reproductive phase change. My trees grown outdoors are invariably shorter as well as stockier with thicker trunks. The trees within the high tunnel are lankier and taller. Almost all of my "precocious" trees were located within the cold frame structure .

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: January 21, 2023, 01:51:09 PM »
Poncirus Plus seedlings, which germinated rather well.

Kabosu seedlings on the far side. No Poncirus genetics.
Meyer Lemon pollinated by Segentrange 026 pollen seedlings on the near side. These seedlings are quite variable as Meyer Lemon is Zygotic.

Despite 026 appearing very similar to Poncirus, it's seedlings resulting from a Conestoga 026 x Meyer Lemon cross show monofoliate and bifoliate, as well as trifoliate seedlings.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: January 21, 2023, 01:41:27 PM »
US 1282 Cold damage in high tunnel. Late season flushing appears to be a big contributor. Poncirus x Cleopatra mandarin hybrid.

US 1281 foliage is rather Poncirus like, but shows no deciduousness. No cold damage observed. Poncirus x Cleopatra mandarin hybrid.

US 1279, the most deciduous of the three, appears to be quite hardy in the high tunnel. May show less hardiness out of doors. Poncirus x Changsha mandarin hybrid.

Cold Hardy Citrus / Re: Viability of seeds from frozen fruit
« on: January 16, 2023, 02:04:45 PM »
There's not much to lose. I have planted immature Clementine seeds and got good germination. The biggest danger I foresee is susceptibility to decay, especially with the adhering flesh.

Cold Hardy Citrus / Re: Viability of seeds from frozen fruit
« on: January 15, 2023, 08:30:21 PM »
A 2-3week seed test at 86°F should provide some answers. If the seeds have a hard seedcoat chances should be better.

Cold Hardy Citrus / Re: looking for most cold hardy poncirus trifoliata
« on: January 14, 2023, 11:11:36 PM »
A trial could be attempted be sowing a large population of the highest percentage of zygotic Poncirus seed available. Provided the seedling population shows variation in hardiness, the hardiest specimens might attain your goal. If your goal is beyond the genetic capability of the seedlings you plant, success would be unlikely.

Cold Hardy Citrus / Re: Citrumelo
« on: January 14, 2023, 11:01:57 PM »
In that case trifoliate should no longer have any influence on the hardiness of the cutting. The resultant cutting's hardiness would be determined by the genetics of the original Citrumelo seedling.

Cold Hardy Citrus / Re: Citrumelo
« on: January 14, 2023, 06:35:22 PM »
There should be a few degrees of additional cold resistance, in part due to deeper dormancy. By increasing the height of graft, the trifoliate understock should have additional influence on cold hardiness of the scion.

kumin, what does it mean to say the seeds of pomelo will be zygotic?

I grew the seeds from my pomelo fruit and they have a few leaves now, can you tell by looking for the largest seedlings to identify the nuclear/clones ?

The most certain test would be to exclude all pollen from the stigma except for pollen from a distinctive foliage type like Poncirus. 100% trifoliate progeny would indicate 100% zygotic seedlings. Alternatively, if the plants are grown to a larger size, there should begin to be a distinction in the growth habits as well as leaf characteristics.
Leaf petiole differences, leaf shapes will vary among zygotic seedlings.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: January 12, 2023, 12:24:02 PM »
Poncirus Plus seeds germinating

Kabosu seeds germinating. They're quite small at this point.

Pomelo seedlings should be 100% zygotic.

Cold Hardy Citrus / Re: Zygotic Poncirus hybrids
« on: January 10, 2023, 06:11:28 AM »
US 1279, 1281, and 1282 are essentially 100% zygotic . Changsha x Poncirus for 1279.
Cleopatra x Poncirus for 1281 and 1282

Cold Hardy Citrus / Re: Is this sun scald?
« on: January 02, 2023, 04:33:54 AM »
I find similar damage on late growth that hasn't sufficiently matured for winter survival. Sunlight may indeed bleach the damaged twigs.

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: December 30, 2022, 03:28:40 PM »
Poncirus Plus fruits were allowed to become very ripe before opening. There was light, detectable sweetness, some wax, but not terribly objectionable. Many seeds, Brix 13.

Meyer Lemon with hybrid seeds. Brix 12. Very good flavor.

Cold Hardy Citrus / Re: Tetraploid Citranges
« on: December 29, 2022, 04:35:17 PM »
Tetraploid Carrizo citrange rootstock (Citrus sinensis Osb.×Poncirus trifoliata L. Raf.) enhances natural chilling stress tolerance of common clementine (Citrus clementina Hort. ex Tan).
J Plant Physiol. 2017 Jul; 214:108-115.
Low temperatures can disturb the development, growth and geographic distribution of plants, particularly cold-sensitive plants in the Mediterranean area, where temperatures can reach seasonally low levels. In citrus crops, scion/rootstock combinations are used to improve fruit production and quality, and increase tolerance to biotic and abiotic stresses. In the last decade, several studies have shown that tetraploid citrus seedlings or rootstocks are more tolerant to abiotic stress than their respective diploid. The objective of this study was to test whether the use of tetraploid rootstocks can improve the chilling tolerance of the scion. We compared physiological and biochemical responses to low seasonal temperatures of common Clementine (Citrus sinensis Osb.×Poncirus trifoliata L. Raf.) grafted on diploid and tetraploid Carrizo citrange rootstocks, named C/2xCC and C/4xCC, respectively. During the coldest months, C/4xCC showed a smaller decrease in net photosynthesis (Pn), stomatal conductance (Gs), chlorophyll fluorescence (Fv/Fm), and starch levels, and lower levels of malondialdehyde and electrolyte leakage than C/2xCC. Specific activities of catalase (CAT), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) were higher in C/4xCC during the cold period, whereas chlorophyll, proline, ascorbate and hydrogen peroxide (H2O2) levels and superoxide dismutase (SOD) activity did not vary significantly between C/4xCC and C/2xCC throughout the study period. Taken together, these results demonstrate that tetraploid Carrizo citrange rootstock improves the chilling tolerance of common clementine (scion) thanks to a part of the antioxidant system.

Tetraploid Citrus may have increased cold tolerance. My very hardiest F2 Citrange is a tetraploid (Conestoga 011).

011 as a young seedling.



A few F˛ Citranges survived -11,8 F ( -24,5 C) in January 2019.

Kumin, you did really a extraordinary breeding and selection, not sure if Poncirus is really much hardier. Only a pity, that frosthardiness and edibility are still in a big distance and will need a lot of further time and work. To my knowledge the only citrus with excellent  fruit when ripe and really frosthardy citrus is Thomasville Citrangequat with hardiness about - 15 ° C but still one problem is that fruit ripens in spring and will be spoilt in winter freeze under -5 ° C.
Tedburn, good point regarding early fruit maturity. Deciduous foliage is also quite important. I see a goal of breeding for Citrus fruit approaching the quality of conventional cultivars on a tree similar to Poncirus, minus the thorns.
Several of my selections approach, but don't quite equal the hardiness of Poncirus. Only one has fruited and while the juice is acceptable as a drink, the flavors are too intense for fresh eating.



A few F˛ Citranges survived -11,8 F ( -24,5 C) in January 2019.

My suggestion is to control the heat source by thermostat.overheating is as detrimental as freezing.

Cold Hardy Citrus / Re: Southeastern Citrus Expo pictures
« on: December 02, 2022, 01:44:02 PM »
Have there been any discussions on next year's location?

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

Cold Hardy Citrus / Re: F2 citrange winter hardiness trial
« on: November 23, 2022, 09:52:30 AM »
Photos of a larger 5* Citrumelo found on a tree that was overlooked earlier.

3 year old Poncirus seedling with a small fruit. If this tree fruits again in the coming year, I may consider it somewhat precocious.

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