The science behind freeze tolerance

[vette-kid]

Curious if anyone had any scientific insight on this. My winter garden send to be mostly freeze tolerant, things like carrots, lettuce, pansies, unknown potato, even a bromiliad have survived a few hours of freezing temperatures. Now I know we don't get anywhere near cold enough to freeze the soil, but I'm curious how some leaves on plants survive the freezing air while others; Cavendish variety bananas, for example; either and die as soon as you got 32.

Is there something in plants that chemical inhibits water from freezing? Shunting if water from the leaves (but they aren't dormant, how would that work)? Or just a tough leaf structure that takes the abuse?

I imagine different plants do it differently, but I'm curious how this works in some of my varieties. I have bananas that are wilting and others that are doing ok. Some damage, but generally just slowing down. What's the difference and what's going on inside the plant that allows it to survive a few hours of freezing?

 

[Chuck]

Curious if anyone had any scientific insight on this. My winter garden send to be mostly freeze tolerant, things like carrots, lettuce, pansies, unknown potato, even a bromiliad have survived a few hours of freezing temperatures. Now I know we don't get anywhere near cold enough to freeze the soil, but I'm curious how some leaves on plants survive the freezing air while others; Cavendish variety bananas, for example; either and die as soon as you got 32.

Is there something in plants that chemical inhibits water from freezing? Shunting if water from the leaves (but they aren't dormant, how would that work)? Or just a tough leaf structure that takes the abuse?

I imagine different plants do it differently, but I'm curious how this works in some of my varieties. I have bananas that are wilting and others that are doing ok. Some damage, but generally just slowing down. What's the difference and what's going on inside the plant that allows it to survive a few hours of freezing?

This is a very complicated subject but to sum it up simply, cold hardiness is regulated by proteins, some of which act as something akin to antifreeze in your car. There are a lot of the super cooling proteins but I guess Dehydrin proteins are probably the most well known. These proteins are a little different with each plant species and that's why some plants don't freeze and others do.

 

[vette-kid]

Very interesting. I had kinda figured along those lines, chemical somehow. It's very interesting.

 

[Chuck]

Very interesting. I had kinda figured along those lines, chemical somehow. It's very interesting.

and complicated

 

[DirtMechanic]

And certain hormones are involved with those amino acids somehow.

Wiki:
"Abscisic acid (ABA) is a plant hormone. ABA functions in many plant developmental processes, including seed and bud dormancy, the control of organ size and stomatal closure. It is especially important for plants in the response to environmental stresses, including drought, soil salinity, cold tolerance, freezing tolerance, heat stress and heavy metal ion tolerance.[5]"

 

[roadrunner]

...
I imagine different plants do it differently, but I'm curious how this works in some of my varieties. I have bananas that are wilting and others that are doing ok. Some damage, but generally just slowing down. What's the difference and what's going on inside the plant that allows it to survive a few hours of freezing?

I agree with everything already said; however, there's another factor to consider...You say you have some bananas that are wilting and others that are doing ok.

If these bananas are of the same variety/species, but you see some that are surviving a mild freeze, it could be a micro-climate at work. I see this a lot in my yard with my large Oak tree, because in effect the oak tree's canopy acts as a blanket over the plants under it and actually can have a significant effect.

I've also seen this in the garden with larger plants, even simple annuals, providing a blanket over smaller plants. I've seen plants die from a cold snap and not more than five feet away the same species that was under a canopy of other plants survived.

(This applies to any plant, I just used bananas as an example....)

 

[DirtMechanic]

Along the lines of plants being smarter than I am, there is also the idea of water needing crystallizing points in order to freeze. Hydrophobic, waxy sprays can give a whole zone of temporary protection. Monosilic acid (silicone) is something I have experienced helping my plants with hot weather and fungi attack and its coating property is a waxlike (hydroponic liquid) coating that separates ice crystal from plant cell. The plants may or may not have what they need internally to the same end, but watch this video, and you can see that even being still could be a cold survival strategy for a plant.

 

[vette-kid]

I agree with everything already said; however, there's another factor to consider...You say you have some bananas that are wilting and others that are doing ok.

If these bananas are of the same variety/species, but you see some that are surviving a mild freeze, it could be a micro-climate at work. I see this a lot in my yard with my large Oak tree, because in effect the oak tree's canopy acts as a blanket over the plants under it and actually can have a significant effect.

I've also seen this in the garden with larger plants, even simple annuals, providing a blanket over smaller plants. I've seen plants die from a cold snap and not more than five feet away the same species that was under a canopy of other plants survived.

(This applies to any plant, I just used bananas as an example....)

Different varieties, dwarf Cavendish vs dwarf Orinoco. But your point is well taken.

 

[roadrunner]

Different varieties, dwarf Cavendish vs dwarf Orinoco. But your point is well taken.

That brings up an interesting question. What's the cold tolerance of those two varieties of banana?

I grow Orinoco (not dwarf) bananas and their foliage dies at the freezing mark. We just had a frost the other day, but temps were above freezing and they are doing fine (although when it's cooler out their growth rate significantly slows, if not stop all together).

 

[vette-kid]

That brings up an interesting question. What's the cold tolerance of those two varieties of banana?

I grow Orinoco (not dwarf) bananas and their foliage dies at the freezing mark. We just had a frost the other day, but temps were above freezing and they are doing fine (although when it's cooler out their growth rate significantly slows, if not stop all together).

I get some damage on the leaves at 32, but not total. And I had a pstem survive 24hrs in the 20s (leaves were all shot though). Cavendish showed damage earlier, although right now mine is under a tree, so it stays a little warmer. My super D Cav has lots of leaf damage, but the stems seem ok and the larger ones are protecting the smaller ones.

I'm borderline for most bananas here. The Orinoco will make it, no problem; but leaves will die. Cavendish takes a bit of luck or ingenuity to get through winter.