Author Topic: F2 citrange winter hardiness trial  (Read 60495 times)

kumin

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Re: F2 citrange winter hardiness trial
« Reply #325 on: May 27, 2021, 10:32:16 AM »
Zitrusgaertner, there was no sun protection provided, per se. However, the planting density certainly provided some shading. The original survivors remain on their own roots, but I've grafted several hundred clones of the originals. Some are grafted on fruiting age Poncirus, others are on young Poncirus seedlings. So, the majority are indeed grafted on Poncirus.

Presently I'm in the long wait until they begin flowering/fruiting. At that point it should become apparent if any are edible, or if they're essentially glorified near-Poncirus relatives.

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #326 on: May 28, 2021, 04:06:53 AM »
Fingers crossed that there are already some plants with edible fruit! Just from theory. I would guess that a backcross with Citrus is is a good option with these F2 survivors.
« Last Edit: May 28, 2021, 04:08:28 AM by mikkel »

kumin

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Re: F2 citrange winter hardiness trial
« Reply #327 on: May 28, 2021, 09:05:38 AM »
Mikkel, being quite close to the original hybrid, selecting for extreme cold hardiness likely selected survivors with predominantly Poncirus genetics. However, unless sterile, they're possibly good candidates, as parents in further crosses.

My present goal is to cross the hardiest selections with Citrandarins. Further selections among that progeny should present more opportunities to find the highly sought after "Hardly edible" results. I'm encouraged by the number of breeders involved in this quest.

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #328 on: May 29, 2021, 04:49:19 PM »
Like always,  one gardener but a hundred planners :) Sorry for being one of those planners...


kumin

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Re: F2 citrange winter hardiness trial
« Reply #329 on: May 29, 2021, 05:47:44 PM »
Mikkel, the reason I'm reluctant to use pure Citrus is twofold: I'm eventually going run out of years, so I'm limited in the number of generations I can grow to fruiting. The other reason is that I need nearly all of the Poncirus hardiness to reliably expect survival in my plant hardiness zone.

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

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

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #330 on: May 29, 2021, 06:29:51 PM »
I thought if you already have a F2 (your C35 seedlings) with almost the hardiness of Poncirus, it would be a good idea to cross it with the original Citrus parent of C35. As you have an almost hardy hybrid, but with still inedible fruits, you have already achieved 1 goal. A backcross with Citrus could bring the focus to edible fruits.
If a plant had edible fruits it would make sense to cross it with Poncirus or with C35.
According to the ideal backcrossing scheme
A x B -> F1 
F1 x F1 -> F2S1
F2S1 x A / B -> F3BC1

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #331 on: May 29, 2021, 06:50:16 PM »
btw have you read about grafting on Limonia spec. (not C.limonia but Limonia the genus)? It's just something I read, but they say that grafts on Limonia flower very soon after grafting, almost immediately. But I am not sure if this also happens with immature grafts.

kumin

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Re: F2 citrange winter hardiness trial
« Reply #332 on: May 29, 2021, 08:04:12 PM »
mikkel, are you referring to grafting onto https://citrusvariety.ucr.edu/citrus/limonia.html ? It appears to induce precocity, but might be very frost sensitive, requiring greenhouse protection. If it consistently promotes precocity it may be worth the expense.

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

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

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

 

Walt

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Re: F2 citrange winter hardiness trial
« Reply #333 on: June 01, 2021, 04:58:24 PM »
Mikkel, the reason I'm reluctant to use pure Citrus is twofold: I'm eventually going run out of years, so I'm limited in the number of generations I can grow to fruiting. The other reason is that I need nearly all of the Poncirus hardiness to reliably expect survival in my plant hardiness zone.

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

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


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

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

That said, I'd be open to making crosses back to citrus if someone in zone 7 or 8 wanted to grow out a bunch of 3/4 citrus seedlings.  No hurry though.  I won't have bloom for a while.  Years.

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #334 on: June 01, 2021, 05:31:02 PM »
Do you see a technical advantage in "wild" crossing? Or is it just your choice?
I do both or better I will do backcrossing in the future :) . But I see more advantages (apart from the long waiting time) in backcrossing, because it is probably easier to plan.

kumin

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Re: F2 citrange winter hardiness trial
« Reply #335 on: June 01, 2021, 05:48:27 PM »
Mikkel, does wild crossing refer to "open pollination", vs controlled pollination? If enough of the breeding stock flowers in a few years, controlled pollinations may become overwhelming, at which point a portion of the crosses may well be open pollinations.

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #336 on: June 01, 2021, 06:56:46 PM »
I use "wild crossing" only in the absence of a good English term for the opposite method of species-restricted crossings as practised in backcrossing. I don't prefer one over the other, I just feel that it is more predictable what to expect from these backcrossings (as you stay within the given genpool). I am interested in any strategy and the reasoning behind it.

kumin

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Re: F2 citrange winter hardiness trial
« Reply #337 on: June 01, 2021, 08:34:46 PM »
Mikkel, perhaps you are referring to outcrossing vs backcrossing within the original parents (sweet orange and Poncirus). Backcrossing should narrow the results more than outcrossing would.
The main reason I want to use the segentranges is that they've gone through a very vigorous screening for cold hardiness. The reason I want to use segentrandarins as breeding partners is potential shorter generational cycles, cold hardiness, lower off flavors, and potential earlier ripening of fruit.

In hindsight I suspect US 852 would have been a good seed source. There are a number of tri-specific cold hardy hybrids. These appear to be vigorous in many cases (Thomasville).
« Last Edit: June 01, 2021, 08:40:17 PM by kumin »

hornad

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Re: F2 citrange winter hardiness trial
« Reply #338 on: June 02, 2021, 12:19:26 AM »
Has anyone crossed Poncirus+ and Changsha yet?
« Last Edit: June 02, 2021, 12:21:32 AM by hornad »

Zitrusgaertner

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Re: F2 citrange winter hardiness trial
« Reply #339 on: June 02, 2021, 03:50:00 AM »
Has anyone crossed Poncirus+ and Changsha yet?

Has anybody used PT+ for any new cross yet? There are a lot of interesting things that could be tried. PT+ X Grapefruit Enzo for example. Enzo has a remarkable hardiness and its fruits are quite frostresistant aswell.

kumin

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Re: F2 citrange winter hardiness trial
« Reply #340 on: June 02, 2021, 06:10:38 AM »
I'm aware of a number of persons in the US that have Poncirus+, but not certain any are mature enough to flower/fruit. I have trees that are likely to flower in 2-3 years. Walt suggests many of the the original Poncirus hybrids should be remade with Poncirus+. The likelihood of hybrids existing in Europe should be better.
2 year old, 2 meters tall Poncirus+.

« Last Edit: June 02, 2021, 06:33:09 AM by kumin »

poncirsguy

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Re: F2 citrange winter hardiness trial
« Reply #341 on: June 02, 2021, 09:33:05 AM »
What is the cold tolerance of poncirus plus.

kumin

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Re: F2 citrange winter hardiness trial
« Reply #342 on: June 02, 2021, 10:43:52 AM »
The lowest temperature mine have encountered to this point has been +10 F (-12C) so not a real challenge. There was no damage. Ilya and other European members may have a better answer for the absolute lowest temperature resistance.

Millet

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Re: F2 citrange winter hardiness trial
« Reply #343 on: June 02, 2021, 11:07:05 AM »
there is no hard and fast cold temperature tolerance for poncirus plus.  It all depends on how slow the winters temperatures cool down, was there a hot spell right before the freeze, how healthy the tree is, how strong the wind, and on and on.

Ilya11

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Re: F2 citrange winter hardiness trial
« Reply #344 on: June 02, 2021, 12:42:46 PM »
I have not seen any winter damage of poncirus for the last 30 years in the Paris region, but winter lows never exceeded -18C (0F). But I know that in Kislovodsk, Russia one plant survived without protection several  nights with -28C (-18F) covered only by snow. It was lost later probably due to the neglect.
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Millet

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Re: F2 citrange winter hardiness trial
« Reply #345 on: June 02, 2021, 02:56:37 PM »
I had a Flying Dragon planted close to the south wall of a metal barn. The first real cold spell it was killed. A member of the forum wrote that if I had planted the tree on the north side of the barn, it would have properly hardened off before the real cold weather arrived, and survived.  I am located at 5,240 ft above sea level in zone 5..

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #346 on: June 03, 2021, 05:11:51 AM »
Mikkel, perhaps you are referring to outcrossing vs backcrossing within the original parents (sweet orange and Poncirus). Backcrossing should narrow the results more than outcrossing would.
The main reason I want to use the segentranges is that they've gone through a very vigorous screening for cold hardiness. The reason I want to use segentrandarins as breeding partners is potential shorter generational cycles, cold hardiness, lower off flavors, and potential earlier ripening of fruit.

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


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

In theory, I imagine a crossing plan as follows:

F1 cross C35 (Pt x orange)

x selfing

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

backcross of the hardiest with Citrus

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

backcross to the same crossing partner like in F2

and so on.

Apart from the time it takes...

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

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

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

Wild hybridisation is good to find new types and new combinations.

Ilya11

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Re: F2 citrange winter hardiness trial
« Reply #347 on: June 03, 2021, 10:41:25 AM »
Many different schemes will work if a very large  hybrid population be used, but for this one needs a fertile zygotic parent.
Best regards,
                       Ilya

Walt

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Re: F2 citrange winter hardiness trial
« Reply #348 on: June 03, 2021, 11:20:18 AM »
Mikkel.  I recently got 5* for crossing with the zygotic citandarins I got last year.  My plans are to citandarin x 5* as well as citandarin x citandarin.  Of course which crosses I make will depend on what blooms.

mikkel

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Re: F2 citrange winter hardiness trial
« Reply #349 on: June 03, 2021, 04:27:25 PM »
@Walt, yes plans are plans and only what flowers flowers... that's the hard truth :)
I found many zygotic seedlings among the 5Star and N1tri seedlings I got as a from @Ilya. Even some monofoliate ones among the 5Stars.
These are good varieties for breeding.

 

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