Author Topic: Poncirus  (Read 3553 times)

drymifolia

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Re: Poncirus
« Reply #25 on: April 26, 2023, 07:23:30 PM »
Kunming is at about 6000 ft. I've seen it called zone 9b, but that seems contradictory given it snows there.

9b just means the average lowest temperature each year over the last 30 years is between 25°F and 30°F, it says nothing about how often it gets that cold or what kind of weather may happen. Plenty of snow can happen in the upper 20s!

Looking at the PlantMaps growing zone map for China (not sure the accuracy) it looks like the area around there ranges from 10a near the lakes and other warm spots, to 6a in the mountains in the northern part of Kunming:


Lyn38

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Re: Poncirus
« Reply #26 on: April 26, 2023, 10:44:38 PM »
I don't have much to add to the conversation except that it makes me happy just knowing that someone brought random feral Poncirus trees home with them.

I have a few I planted from seed this spring and those tiny little trees are the most vigorous seedlings. They look like they want to take over the world. I just like them.

mikkel

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Re: Poncirus
« Reply #27 on: April 26, 2023, 10:52:56 PM »
It would be interesting to know if Poncirus polyandra has the same fruit characteristic as trifoliata.
If so, the resinous fruits might not be related to winter hardiness. because polyandra is much less winter hardy than trifoliata.
This would raise the hope that one could breed out these characteristics and still retain a hardy plant.

It's not the cleanest article (there are some noteworthy typos), but...
https://www.sciencedirect.com/science/article/pii/S0888754323000617

This suggests polyandra has cold-signaling genes and at least the potential for increased cold-hardiness relative to citrus. How much is unstated, and they never explicitly compare it to trifoliata.

Kunming is at about 6000 ft. I've seen it called zone 9b, but that seems contradictory given it snows there.

My P.polyandra nearly died at -6°C. It is not very coldhardy. I would say there are some Citrus that are more coldhardy than polyandra.

bussone

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Re: Poncirus
« Reply #28 on: April 27, 2023, 10:50:47 AM »
It would be interesting to know if Poncirus polyandra has the same fruit characteristic as trifoliata.
If so, the resinous fruits might not be related to winter hardiness. because polyandra is much less winter hardy than trifoliata.
This would raise the hope that one could breed out these characteristics and still retain a hardy plant.

It's not the cleanest article (there are some noteworthy typos), but...
https://www.sciencedirect.com/science/article/pii/S0888754323000617

This suggests polyandra has cold-signaling genes and at least the potential for increased cold-hardiness relative to citrus. How much is unstated, and they never explicitly compare it to trifoliata.

Kunming is at about 6000 ft. I've seen it called zone 9b, but that seems contradictory given it snows there.

My P.polyandra nearly died at -6°C. It is not very coldhardy. I would say there are some Citrus that are more coldhardy than polyandra.

I know it's commonly assumed polyandra is a missing link for trifoliata. But it's also possible that polyandra is a poncirus species whose deciduous genes were lost or stopped working. It may not be an intermediary between citrus and poncirus trifoliata.

Till

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Re: Poncirus
« Reply #29 on: May 02, 2023, 02:24:25 AM »
I am not sure that there is any link between bad taste and hardiness. Changsha is pretty hardy but has no bad taste. Certain Poncirus hybrids have a relatively good taste without being especially frost tender. We know of much better tasting Poncirus types that are as hardy as the bad tasting ones.
It is more wise I think to look for scientific ariticles about Poncirus hardiness than to speculate about a link between taste and frost hardiness. Keys to winter hardiness are certainly winter dormancy, early flowering and sprooting combined with early stop of growth so that twigs can harden off, deciduousness, and sunken stomata in the twigs (as a reaction to quasi arid winter conditions when eath is frozen). I suppose that Poncirus has other mechanisms too as the ability to reduce humidity in its twigs and the ability to reconnect the water column in its wooden parts when ice crystals have disrupted it. Other frost hardy tree can do that.
Regarding early sprooting and early stop of growth, I have seen that Poncirus varieties differ greatly. Some will never have a second growth in late summer or autumn even when they are in a warm green house. Others flower again in autumn even when they grow outside. I suppose that winter dormancy is regulated by different independant mechanisms or genes, some that are sensitive to day length others that are sensitive to temperature. I further assume that these mechanisms are active in different varieties to a different degree so that some are mainly sensitive to temperature others also to day length. I have though no scientific information about that. I only remember an lexicon article that states that Poncirus is sensitive to day length. What I see myself is though a mixed picture.

bussone

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Re: Poncirus
« Reply #30 on: May 02, 2023, 10:53:16 AM »
I only remember an lexicon article that states that Poncirus is sensitive to day length. What I see myself is though a mixed picture.

I recall reading, but not where, that mountain species favor a daylight-length strategy and plains species favor a temperature-based strategy. Mind you, humidity often has a negative correlation with altitude (elevation tends to be dry), so this may also be a desert feature.

Regardless, poncirus seems to have arisen at elevation.