Frost and Cold Tolerant Tomato Breeding including epigenetic and regular genetic

[Cathy A]

Off the top of my head, it's difficult to think of sweet fruits that prefer cooler temperatures. My earliest berries are honeyberries, which are fairly sweet, but they aren't much earlier than strawberries. It gets pretty warm and sunny before I get any sweet fruit.

I wonder how much of the effect is temperature, and how much is long days of bright sunlight. This could be tested under controlled conditions, such as in a heated greenhouse with good sun exposure but no artificial light.

Can some fruits (including tomatoes) be ripened earlier in warm conditions, despite short days?

Can some be ripened in relatively cool weather if given long days of bright artifical light?

[Joseph Lofthouse]

Biological processes happen quicker at higher temperatures. An 18 degree F change in temperature doubles the rate of reaction.

Applying that to tomatoes....

Say it takes 56 days from flower to ripe fruit in my garden.
Then lets say another garden's average temperature is 5 degrees F warmer than mine. That tomato could be expected to ripen 40 days after flowering.

Or in my case, because my average temperatures are lower, if the catalog says that a tomato takes 70 days to maturity, it actually takes 90 days in my garden. That's why when buying commercial seeds, I only buy 55 DTM tomatoes.

[Steph S]

The enzymes involved in producing lycopene and various flavor components in tomato ripening are very temperature sensitive.   This is why they tell you never to refrigerate a tomato.
Also some folks have reported that they bought supermarket maters and let them sit in a warm place for several days to improve the flavor.  Because those fruits have been picked at breaker and then refrigerated during shipping and storage.
There seems to be a fair bit of genetic variation in temperature sensitivity, at least there are some varieties that produce tasty fruit in cooler weather.   Ripening time can be longer though, across the board. But still, it is possible to select for tasty cool weather tomatoes.

[William Schlegel]

Various weather outlets suggest a low of 37 to 38 tonight. I expect some minor frost damage in the frost pocket gardens. Unusual for June 19th.

[reed]

I have the opposite problem, 82F at 6 am and little chance of rain in the next ten days. On the positive side, I have ripe cherry tomatoes and they are so, so good. 

[William Schlegel]

No frost, fog came in. Everything is fine. Still cold for this late in June though.

[Joseph Lofthouse]

I had a great frost yesterday. It made it simple to see which lines have a lot of frost resistance, and which have little.

I wasn't surprised that the Profoundly Promiscuous and Totally Tasty Tomatoes project carried a lot of frost tolerance. They descended from Jagodka, the winner of my frost/cold tolerance trials, and from LA1777 which was collected at 11,000 feet in the Andes.

As expected Hummingbird tomato (50% pimpinelifolium) got hit hard.

And Solanum galapagense got magnificently damaged.

A line with a lot of frost tolerance that I didn't expect was  F3 of SunSugar X R18.

[William Schlegel]

One of the most obvious potentially cold tolerant tomatoes I've seen this spring is 50% current tomato from two different accessions. However, because our projects are intertwined, it is also 1/4 Big Hill which means it is 1/8th Jagodka. Last fall it was R18 that was the real standout.

In the direct seeding of orange Promiscuous (The One sub-strain) x Mission Mountain repeated light frosts have done some damage and I really think it might be genetic based on some individuals looking quite sad interspersed with healthy individuals. Frost has never affected the direct seedings this much in the spring before in the 7 years I've been direct seeding.

I haven't seen any frost damage in the Promiscuous x LA2329 and MMM x (Promiscuous x LA2329) direct seeded garden. Maybe the extra fuzz on the seedlings is protective.

[ThomatoGarden]

When The Greenhouse got hit by frost 2021 twice (my fault, heating failure) only all Paul Robson Plants survived without any damage, i think it was random but who knows, maybe they are a bit cold resistant.