Tomatoes resistant to cold weather

[Lindalana]

Am seeing Tania is growing a number of cold resistant tomatoes from old USSR breeder Saraev this year. Saraev is know for his work breeding early, cold resistant and direct seed for short cold summer areas varieties. Tania seems will be offering a number of them this year.
I have grown 0-33 from Saraev collection and it is one tough tomato. Will grow again. That old fashioned taste lots of people like.
But reading few papers still avail on growing such tomatoes, it is mentioned that tomatoes that were bred for this specific purpose- as in being cold tolerant or able to be grown from seed stage right in the garden early on- description states those seeds go into ground when willow gets first buds/ leaves- seeds to continue to have traits it was bred for HAS to be submitted to cold weather at least at some point. Otherwise new saved seeds in about 3 generations will "loose" or "put to sleep" traits they were bred for.
Hmm, so is cold stress period that I give to seedlings as per Ami info is good enough or I should literally get my seedlings out real early and let them have it?

[bower]

Very interesting... I hope someone can answer your question.

I recall reading that cold tolerance in seeds vs in plants is under separate genetic control. Whether the gene expression of both traits is activated by cold exposure of the plant, I don't know. But a given variety may have one trait and not the other, or both, that is aside from the question of gene expression and how it is triggered by environment.

I always use a heat mat for germinating my tomato seeds.. the seedlings are afterwards exposed to cold. Some plants which are started this way, go to my mother's garden, where they have to tolerate the outdoor cold unprotected. Last year she had me turn under some damaged fruit of several kinds which she'd grown. In late spring some tomato plants germinated from those seeds. These plants are all PL, so we know they are Chernomor seeds and no crossed seeds either, as this was the only PL in the garden. None of the others survived winter and germinated. The seeds of the Chernomor I grew for her are 3 + generations of growing here, but in my greenhouse not outdoors, and always started on a heat mat. So the seed trait of surviving winter and germinating in rather cold soil, seems to be have been activated without the most extreme 'cold treatment' of seeds in this case. Only the plant was tested by cold after maturing and being set out.

I have wondered about the effects on seeds, from environmental conditions affecting that particular fruit as it ripened, that seed was saved from.... earliest and latest fruit are often the ones we save seed from, and experience the most stressful conditions.

[dustdevil]

Tomato seeds need to be taken from fruit of a plant that is true to type...that would include cold resistance, short season, etc. that you mention above.

[AKmark]

I didn't find 0-33 to be anything special, it's pretty ok, but Sasha's Altai produced bigger and better tasting fruit, as a like variety, and both were wasted by a light frost. Personally, other indeterminate varieties I grew did much better, Early Girl, 4th of July, PL Early Girl X PL Black Krim, Brandywine X Bloody Butcher, Bloody Butcher, Matina, Summer Girl, and Moscvich all were done side by side.
I have a good list of duds too, but we won't bash today.

[Fusion_power]

Lindalana, Most of the cold tolerance in tomatoes is epigenetic meaning that they lose the trait after a few generations of not being exposed to cold. This is typical of several stress tolerance traits such as heat tolerance, light intensity tolerance, etc.

[Lindalana]

Thanks for answers!
To clarify- what does counts as exposure to cold? At which stage and how much? I like the idea that I could move plant out earlier under row cover with some soil warming lets say and expect it get decent results early.
This spring I did notice distinct difference in 0-33 being more resistant to damage although plants were somewhat protected i.e. we did not have direct frost. Knowing what I know now I could put pots out earlier.

[MrBig46]

Originally Posted by Fusion_power

Lindalana, Most of the cold tolerance in tomatoes is epigenetic meaning that they lose the trait after a few generations of not being exposed to cold. This is typical of several stress tolerance traits such as heat tolerance, light intensity tolerance, etc.

Am I to understand that after all these years 0-33 has been no tolerance to low temperatures? Epigenetic in this case means that the tomato irretrievably lost resistance to low temperatures? Can in some way again regain tolerance to low temperatures (eg hardening) ?
Vladimír

[PhilaGardener]

Very interesting!

Sounds like a good candidate for wintersowing. (Anyone not familiar with this should visit Trudi's nice site at http://www.wintersown.org/ for more info and SASE seeds).

[Fusion_power]

MrBig, yes, you can expose a tomato to increasingly cold temps to re-establish epigenetic cold tolerance. However, the fundamental photosynthesis cycle for tomato plants is disrupted by long term exposure to temps below 50 degrees. The cold tolerance that O-33 and similar varieties display is only effective for short term exposure to temps below freezing. One night at 25 (-5C) degrees followed by 2 weeks of warmer weather at 60 (16C) is not a problem. One night at 25 degrees followed by 2 weeks at 35 (2C) to 40 (5C) degrees is a big issue and will usually severely disable or kill even the most cold tolerant tomatoes available.

[MrBig46]

Thank you for the information.
Vladimír

[AKmark]

Here are some pics of my garden after a few frosts and temps around 30 for a few nights.
I did save parts of some plants by covering them with plastic. The plants that did the best were un-topped indeterminate's that took the frost, on their tops, but the shielded bottoms survived and produced a bit more fruit.
I sure have a mess to clean up that for sure.

0-33, Sash'a Altai, Glacier, Polar Beauty, and indeterminate's.

[Lindalana]

Nice yields!
I have not tried Sasha Altai, but have seeds.
I think those types of tomatoes do work well for WS and one gets results somewhere in August as from transplant.
For me- I like that I could put tomatoes out early, get the production by beginning of July and as true dets- they done and leave me less care for rest of the summer when I am looking forward to my mid and late varieties to enjoy.
Also one has to remember that early types might be bred in the areas where canning, pickling, making juices and dehydrating i.e. preserving supplies for long haul is main goal.
Tomato that grown for taste alone might not be so tasty when canned specially as whole tomato and does not have qualities for best pickling tomato as in having thin skin getting mushy with time etc.

[MrBig46]

I read that attempts have been made with the becoming hardened the seeds before sowing. Plants from the seeds in this way stimulated are characterized by a shorter growing period and better resist declines temperature (tests conducted three years). Anyone have similar information?
Vladimír

[Gerardo]

Originally Posted by Fusion_power

MrBig, yes, you can expose a tomato to increasingly cold temps to re-establish epigenetic cold tolerance. However, the fundamental photosynthesis cycle for tomato plants is disrupted by long term exposure to temps below 50 degrees. The cold tolerance that O-33 and similar varieties display is only effective for short term exposure to temps below freezing. One night at 25 (-5C) degrees followed by 2 weeks of warmer weather at 60 (16C) is not a problem. One night at 25 degrees followed by 2 weeks at 35 (2C) to 40 (5C) degrees is a big issue and will usually severely disable or kill even the most cold tolerant tomatoes available.

Great temperature ranges, relatively easy to remember. So one night in the not quite freezer temp plus a week or so of typical refrigeration temps (2-5C) will put em down. Thank u!

[bower]

It's not uncommon for tomatoes in my cold climate to be exposed during the spring season to three consecutive days that reach 50 F or less, in the greenhouse. That span is tolerated pretty well by anything "cold tolerant", but when it happened just at the time of transplant in 2013, I had some duplicates of the same varieties that were held back and planted out 2-3 days later after the cold spell had ended. The later planted 'extras' ripened first fruit 5-10 days earlier than the ones that had cold stress just after transplant. That result was a warning to me, that I may not get earlier fruit by putting the plants into an environment that is just too stressful.

Since then I've been holding my plants and watching the weather for an early warm spell of at least three days, when I can plant them out with minimal stress. Also using AKMark's tip to warm water at transplant time to reduce the stress (I use a kelp solution). The original question about seed germination in cold soil, obviously, avoids that issue because there is no transplant stress if you can direct sow, or even winter sow your seeds.

The soil temperature has a huge impact on cold tolerance. This is why we see very different 'tolerance' in plants at the end of the season, which already have strong root systems and the benefit of summer's warming of the soil, IMO. There is a difference in containers vs in ground, because containers warm up sooner. But seedlings which already have strong root systems will perform and tolerate cold stress better whether in containers or in the ground, I think. All of my seedlings have great roots because I put some bone meal in the cup. They are cold stressed but they get enough warmth over time to take up and store some of the elements they need for further growth. I have compared with seedlings that got liquid ferts in "promix" type medium instead, and they are not as good, or not consistent in the quality of their roots, and their performance is spotty afaict and I think this is the reason.

So there are a lot of environmental factors and 'tweaks' we can do to improve results in a cold climate or a cold spring, apart from the genetics. Still there's no doubt from my experience, that some varieties can do much better than others in the cold. Some types are damaged by exposure to excess cold in spring, and will not do well afterwards no matter how lovely the weather.