Cold tolerant tomatoes, right down Joseph's alley.

[Joseph Lofthouse]

Since the skies were clear, I ran a radiant cooling test last night...

I took a piece of insulation board and attached probes from a digital thermometer. Then I placed it outdoors so that one probe was facing up towards the sky, and the second probe was facing down towards the ground. Presumably the bottom probe would measure air temperature, and the top probe would measure the radiant cooling effect.

The difference in temperatures between the two probes was 8 to 9 F. That fits well with observations of my garden in which plant leafs may be damaged by frost if the air temperature falls below 40 F on a clear night.

My garden probably has a slightly higher cooling effect because there are no trees or buildings nearby to block part of the sky. And I'd rate the sky clarity last night as 9 on a scale of 10.

[DarJones]

I am working on defining the basic concepts and issues with developing a cold tolerant tomato. These are some more thoughts along lines I've already looked at and adding some new items. The first and most important statement is that there are a bit over 500 genes involved in the stress response biopaths for S. Lycopersicum tomato. At least 1/3 of them are not activated by cold temperatures. By comparison, S. Habrochaites activates nearly 200 unique genes when exposed to cold. The number of genes involved indicates that multiple external traits are invilved.

One item I needed to define is exactly what temps a tomato can stand.

120°F = Severe heat, but if plenty of water is available, the plants are fine. This temp is way above levels at which pollination can take place. Plants with heavy fruit set may show stress.

92°F = This is the temp at which pollen starts clumping and blossoms begin to drop.

70°F to 92°F = This is the goldilocks zone. Tomatoes grow prolifically, flowers set readily, plants need maximum fertility in the soil. The high end of this range is optimum for spread of several foliage diseases.

65°F to 72°F = the best temperature to grow seedlings.

50°F to 65°F = this is the beginning of cold stress. Tomato plants in this range grow slowly, often produce anthcyanins (turn purple), and become pale green from loss of chlorophyll function.

32°F to 50°F = This is the range where normal tomato plants show severe cold stress. Leaves shrivel, turn yellow, wilt, stems lose turgor, roots stop absorbing water.

28°F to 32°F = This is the maximum range most tomatoes can withstand without freezing. Note that if frost forms on the leaves, then the leaves will freeze and die. The plant may live and can form new leaves, but the stunting effects take quite a bit of time to overcome.

22°F to 28°F = This is the range that a few select varieties can withstand for brief periods of time but stipulating that frost on the leaves will still kill them.

15°F to 22°F = This is the range that a few Russian cultivars are reported to survive, again only if frost does not form. The reports I have read indicate that this tolerance is only for a limited time period, in other words, repeated low temps for 3 days or more will still kill the plants.

0°F to 15°F = A few Russian cultivars are able to handle temps this low for brief periods of time. This is the low end of the range that wild tomato species S. Habrochaites, S. Chilense, and S. Lycopersicoides can withstand.

As the temperature goes below 60°F, tomato plants enter a state where normal photosynthesis ceases. Sugar accumulates in the leaves, rubisco - a crucial chemical in the plant- begins to be deactivated by free radicles. This process causes the leaves to become dysfunctional in such a way that they can not recover. One very special trick that greenhouse growers MUST know is that if plants are exposed to overnight lows below 45°F then the greenhouse must be let rise to a high temp near 100°F the next day. If this is done, then the plants totally reverse all effects of being too cold the night before.

Here are a few of the breeding objectives.

Able to tolerate extremely low temps for short periods of time
There are several components to this high order trait. The leaves must be able to close stomata to avoid dessication. The leaves must be thicker than normal again to avoid desiccation. The stem must be able to maintain elasticity and conduit ability for photosynthate from the leaves and nutrients from the roots. The roots must be able to maintain absorption of nutrients.

Fruit must be able to tolerate freezing temps
The fruit must not freeze damage as a result of cold where typical damage is gray soft areas inside the fruit skin. The fruit must maintain expansion even when cold temps limit biological processes. The plant must be capable of translocating nutrients from the leaves and roots to the fruits.

Flavor must be maintained regardless of temperature, especially at fruit maturity
This requires that the leaves must be able to produce the volatiles that compose aroma and the terpenes associated with flavor. There is an implied problem with calcium channel signalling at low temperatures. Selection must be maintained for fruit that are healthy and well developed.

Pollination must be able to occur at temps from 32 to 50 degrees F
There are several issues with pollination since most tomato plants do not set fruit at temps below 50F. The first is precocious flowering which would seem to be a required trait. Another is for pollen production which is necessary for fruit enlargement to occur. I have LA2006 with the ft gene for flowering at low temps, but that does not necessarily include production of pollen. S. Habrochaites produces pollen in the desired temp range so it may be the best source of these genes. I do not want to use the parthenocarpic genes because they infer several physiological processes are dysfunctional.

Able to grow at low temps where most tomatoes shrivel up and shiver (range 32 to 50 degrees F)
This is currently a non-existent high order trait in S. Lycopersicum. I am not certain if any of the cold tolerant cultivated varieties I have accumulated so far will help any in this regard. I have researched enough to know that this ability is in S. Habrochaites and in S. Lycopersicoides. I plan on relying heavily on these species to bring in the required traits.

Able to grow and produce in a cool climate, i.e. with less growing degree days for the season
This is a significant new direction for the breeding work. Areas such as large parts of Oregon and Washington have normal summer temps that are almost too cool for tomatoes to grow. The physiological adaptations required for growing at 32 to 50 degrees F should also help with growth in areas that have low average temps. The objective then should be to reduce the number of growing degree days for tomatoes to produce a crop.

Here are varieties I have accumulated so far and reasons for including them in a cold tolerance breeding program.

Bellstar - Jointless and was developed in Canada with a degree of cold tolerance
Wheatley's Frost Resistant - has cold tolerance, but seems oriented toward late season rather than early spring
Glacier - Small early and productive with some cold tolerance
Stupice - Small early and productive with some cold tolerance
Siberian - Small early and productive with some cold tolerance
Tastiheart - my selection that survived 22 degrees F April 7th 2007
LA2006 - ft gene for setting fruit at low temps.
PI 126256 - Noted for high cold tolerance

Crosses I plan on making to see what can be done:
Kimberly X Eva Purple Ball - to move the precocious flowering gene into a larger fruited variety
(BBxEPB) X LA4026 to combine jointless, high lycopene, F1, F2, F3
LA4454 X Druzba to combine the sucr gene with a good flavored line
Tastiheart X LA2006 to combine cold tolerance with fruit set at 40°F
Perth Pride X (disease tolerant breeding line from R. Gardner) to get ph3 into a dwarf
Doublerich X LA0722 to move the ascorbic acid gene(s) into a high vitamin C line. Hopefully will be able to increase vitamin C significantly.
Nepal X ? - To bring in good flavor genes
KBX X Bellstar - to get the jointless gene into a good flavored large fruited orange.
Tastiheart X PI 126256
Atkinson X LA3969 - to move the chromosome 12 segment into an adapted southern variety

I'll add more crosses as I think of them.

DarJones

[raymondo]

Dar, by jointless, do you mean the peduncle is unjointed? and whatever it means, what advantage does jointlessness confer?

[Joseph Lofthouse]

Jan 4, 2013 1:59:37 GMT -5 DarJones said:

Pollination must be able to occur at temps from 32 to 50 degrees F
There are several issues with pollination since most tomato plants do not set fruit at temps below 50F.

I think that this may be an important trait for my garden... We have sufficient growing degree days, but due to the severe radiant cooling at night it takes a long time for tomatoes to start setting fruit.

[ferdzy]

The first year we had this garden was a terrible one for tomatoes (and most things, actually). I don't think it got above 20°C (about 70°F) all summer, and if it did, it was for minutes at a time. Mostly it didn't even get all that close to 20°C - 16°C was probably about average. Say about 62°F? It was also cloudy and rainy a very large part of the time. Since it was our first year with this garden with its sandy rather acidic soil, our crop was dismal. Plus we ended up putting in bought seedlings late, because we killed our own starts by watering them from our deep well, which turned out to be full of salt.

Still, we did get a few tomatoes... Bellestar wasn't one but a farmer friend grew it, totally neglected it, then let us pick our own, and it was amazing. Absolutely loaded with good tasting tomatoes. (Not the best tasting I've ever had, but up there at the 80% mark, say.)

The ones I remember doing surprisingly well were Garden Peach and Green Zebra. I think Paul Robeson managed to squeeze a few out, but I don't know if it was better than average or if I just remember it because it was the first year we grew it.

We didn't grow Federle that year which is too bad because my experience with it since then is that it really doesn't like hot weather, and stops forming tomatoes when it gets much above 22°C. I noticed this (hot, dry) summer that after a first early flush (when it was still quite cool) it did bugger-all for most of the summer then started forming tomatoes like crazy in the fall when it cooled down, but it was too late for them to ripen. So it might be one to trial.

The only tomato besides Bellestar on your list that I've tried so far was Eva Purple Ball. We found it not productive (but this was a hotter summer when we grew it) and we didn't like the flavour either. Too bad. It was a cute and distinctive looking tomato.

[atash]

Fruit must be able to tolerate freezing temps
The fruit must not freeze damage as a result of cold where typical damage is gray soft areas inside the fruit skin. The fruit must maintain expansion even when cold temps limit biological processes. The plant must be capable of translocating nutrients from the leaves and roots to the fruits.

Oddly enough, this already exists. I've seen them. Quite a few of Tom's tomatoes have genes that cause the fruit to survive unscathed temperatures that kill the vines.

Tom says high pectin levels.

Betimes Macbeth has these genes; the tomatoes last weirdly long. I dunno if they have the "non-ripening gene"--they never ripen soft--or if it's just the high pectin levels. They stay firm for months. I suspect that if either picked and carefully laid out with lots of air around them, or moved out of the weather, the tomatoes would last well into the winter.

I do not want to use the parthenocarpic genes because they infer several physiological processes are dysfunctional.

Well, in bad years, those cause a lot of local tomatoes to waste energy on fruits that have no flavor and the consistency of wet toilet paper. I don't bother to harvest them, and I'm not all that picky. Unfortunately those genes are all over the place because someone thought they were a great idea. I concur that they are more trouble than they are worth. Besides, ultimately, I do want seeds...

Here are varieties I have accumulated so far and reasons for including them in a cold tolerance breeding program.

I suggest adding Forest Fire, bred by our very own Tim Peters. Unfortunately it does have the parthenocarpic trait. But it's a precocious bloomer, ripens easily, and has firm fruit that does not split easily, an important trait here as it is impossible to stop the clouds from dumping rain. I hate it when people tell me that splitting and blossom end rot are my fault because I'm watering too much. (I never water tomatoes in this climate. They're thinking of California not Washington). It has an interesting pedigree.

Betimes Macbeth has even firmer fruit.

Of the wild species, S. habrochaites sounds like the best bet for growing comfortably in the PNW. S. peruvianum is probably an even better match for the climate (ranging into higher latitudes), but it does not cross readily to domesticated tomatoes. A lot of things from their part of the world flourish here from spring through autumn, but most won't survive the winters unless as freeze-backs; our frosts can last for 3 weeks at a time. I have a Saracha (no idea what species) whose younger leaves got nipped by frost recently--and it was collected around 12,000 feet (probably had human help getting up that high, and perhaps the shelter of a house; they're grown by locals as ornamentals). I have some sort of unidentified Ericoid from around 10,000 feet that froze back to the base. About 30F just at night nearly killed it. Somewhere around 11,000 feet is probably about frost level, but a lot of tender things hide among rocks and survive at higher altitudes despite having no frost resistance. Ullucos from that elevation tolerate no more frost than any other (speaking from personal experience...).

S. lycopersicoides probably tolerates some real frost, ranging further south and higher up than S. habrochaites, but it needs significant artificial help to cross to a tomato--to make the introgressions they had to do embryo rescue. And, it come from very dry habitats in southern Peru and northern Chile. Probably averse to higher rainfall levels.

I would bet that S. habrochaites has day-length sensitivities that will have to be bred out. Not to mention the fruit is said to be bitter. S. lycopersicoides occurs near the edge of the tropics and might not be day-length sensitive, or less so.

[DarJones]

S. Habrochaites is arguably the easiest to introgress and has documented genetics for growing in cold conditions. S. Lycopersicoides is probably much more cold tolerant, but the genetic difficulty of introgressing traits will be significantly higher. I already have LA3969 which is an introgression line with a big chunk of chromosome 12 from S. Habrochaites and has been proven to show high levels of cold tolerance. I have about 40 introgression lines for S. Lycopersicoides each containing small chunks of the 12 chromosomes and covering about 95% of the Lycopersicoides genome. I don't see any significant barriers to working with these genetics. I do see this taking a long time to achieve significant results.

I will ask Tom about Betimes Macbeth and any others he feels have significant cold tolerance. The traits that are needed are widely dispersed in the genome so it will take a while just to assemble all the varieties needed.

DarJones

[Joseph Lofthouse]

Jan 4, 2013 13:32:49 GMT -5 atash said:

Betimes Macbeth has these genes; the tomatoes last weirdly long. I dunno if they have the "non-ripening gene"--they never ripen soft--or if it's just the high pectin levels. They stay firm for months. I suspect that if either picked and carefully laid out with lots of air around them, or moved out of the weather, the tomatoes would last well into the winter.

I had tomatoes for supper tonight. They were harvested the last week of September or the first week of October. They weren't the best tomatoes I have eaten, but most of them were better tasting than what is currently available at the grocery store. They sat on the porch until it got too cold for them, then they were moved onto the kitchen counter. They are wrinkled, but not spoiling: Quite firm.

[steev]

"They are wrinkled, but not spoiling: quite firm." Sounds like my sweetheart.

[12540dumont]

Over the weekend we ate the last of the cherry tomatoes from Belgium and the last of the Santa Anas. Both of these were still tasty and firm.

Dar, I can't wait to try the Italian storage tomatoes.

The Belgium Cherries were actually better after they were stored!

[atash]

Apparently I oversimplified the matter. Tom says "yes, pectin", but a whole lot of other issues as well. Involves a lot of sesquipedalian words such as are found in white papers.

[Joseph Lofthouse]

I tasted some potato berries this fall. They were OK once they matured enough to turn yellow(ish). I bet there are some long-keeping genes in that section of the Solanaceae.

[DarJones]

Sesquipedalian? I've been told that I have an idiosyncrasy of using grandiloquent histrionics to discountenance impecunious abecedarians.

Tom has a good idea of the difficulties involved. The basic problem is that tomatoes originated in the tropics and are adapted to temperatures from 70F to 90F. Take them above that range and the plants are happy so long as they have plenty of water. Take them below that range and they get sick fast. By contrast, there are plenty of plants that are adapted to living and growing at temperatures from 0F to 50F such as hairy vetch.

My goal is to change the above. I know it won't be easy.

DarJones - who has recently suffered severe headaches from reading a bunch of those white papers as per links in this thread.

[ottawagardener]

Certainly physalias can be very long lasting in their husks. You ate potato berries... you're a brave soul. I've grown some long keeper types like Mystery Keeper originally from Mapple Farms. I can't say I love them.

I prefer tomatoes that dry quickly on the line so that I can eat them sun dried.

[12540dumont]

Dar, you are never bombastic. Eloquent, illuminating, insightful? yes, and sometimes I need a dictionary to figure out what you and Joseph are on about, but I don't think you should call me an abecedarian....I prefer greenhorn or even trifler.

Sniff. I think I've been insulted.