Heat tolerant, Heat Resistant, Hot Climate Tomato Varieties and breeding

[Alex]

While growing F2 generation of tomatoes, typhoon destroyed all leaves, leaving 90% of bushes bare. But a month later, 90% of tomato plants had recovered, giving me approximately 100-110 plants, enough to continue selection. Successful crossbreeding is confirmed by segregation of traits. Aphid infestation varies depending on color and shape of leaves. For example, green leaves are more susceptible to aphid infestation than blue ones. Currently flavor varies between flavors of both parents.
Photo shows an unripe orange-red F2 tomato plant:

Photo shows a ripe orange-red F2 tomato plant:

Productivity:

[Alex]

Color range ranges from orange-red, light red, to dark red. There are two-toned orange and red fruits (bicolor), and some with a white core. There is no obvious yellow color, but they become orange-red. Flavor, after more tests, is broader than that of parents and includes some rare plants with a super-sour taste. Fruit size varies between sizes of both parents; it is mostly medium, but one plant produces fruits larger than its parents. The most common shape of tomatoes is cherry, sometimes grape.
Based on these observations, it can be assumed that (hypotheses):
1) Texas wild cherry tomato two centuries ago could have been twice as large, or my Sara's tomato is not pure.
2) no obvious signs of S.Cheesmaniae, S.Pimpinellifolium were detected, but S.Galapagense, casting doubt on Sara's genetics. This is understandable, as most wild tomatoes on Galapagos Islands hybridize with each other, and Sara's tomato could very well be S.Cheesmaniae x S.Galapagense x S.Pimpinellifolium hybrid or even (the most likely to me) S.Cheesmaniae x S.Galapagense x S. lycopersicum var. cerasiforme hybrid.
Experience has shown that pure S. Galapagense cannot grow in my climate due to high humidity. Its hybrids do poorly, but produce only a few fruits before dying. In this case, some plants (no more than 3% of population) in F2 exhibit predominantly S. Galapagense traits, and they have already died.
carolyn137: "I was the one who introduced Sara's Galapagos and Amy named it and yes,it is a stable interspecies hybrid as Dr. Chatelet told me and he's at theTGRC in Davis, CA". That is, he only said that it was a stable interspecies cross, but he did not say that it was a S.Cheesmaniae x S.Pimpinellifolium hybrid.

[Alex]

Bicolor:

Red:

Productivity:

8 kg/week (100 plants):

[Adrian]

Hi Alex,
I have a question,
The flowers of texas x sara  are able to be fecondated at a temperature above of 35°C?

[Alex]

Hi Adrian,
This year we're cooler due to La Niña, with temperatures not reaching 35°C (95°F), but 32°C (90°F). In previous years, no tomatoes produced fruit in June; it was hotter. La Niña occurs here every 3-7 years. It's impossible to answer your question this year.

[Alex]

Regarding cracking, situation is as follows. In my case, orange color is due to S. galapagense genetics, which is naturally tough-skinned and resistant to cracking. It has been observed in practice that more orange tomatoes in F2 are less susceptible to cracking than those with a predominance of red. Therefore, in this particular case, cracking depends on fruit color.

Given heterosis, I predict fruits will be twice as large, larger than mother plants.

This prediction did not come true for F1, but in F2 for 1% of population.

And perhaps in June, when weather is at its hottest, I'll conduct selection for heat tolerance.

Due to La Niña effect, which brought cooler temperatures and more rain, June was not the hottest month of summer.

[Alex]

Fruit size varies between sizes of both parents; it is mostly medium, but one plant produces fruits larger than its parents.

Currently, two plants are producing fruit that are larger than crossed parents. One is dark red, tough-skinned, not sweet, and has a standard tomato flavor; the other is orange-red, soft-skinned, and sweet.

[Alex]

A question for experts. Since several genes and their combinations are responsible for large fruits, it's not easy to stabilize them. What's minimum number of F3 plants to plant from seeds, selected from F2 plants, that exhibit large fruits?

[Joseph Lofthouse]

Here's what the F2 looked like when I crossed a beefsteak with a saladette.

[Alex]

According to preliminary data, heat resistance is inherited; in my case, it's not manifested only in dwarf plants, whose leaves were constantly scorched throughout June. Further clarification is impossible during July and August, as a super typhoon is expected in two days, which will destroy everything.

[Alex]

Unfortunately, typhoon destroyed almost all my plants, it was very strong and passed very close to my garden.

[Alex]

The following five lines were selected for the next generation of F3:
- bicolor cherry, standard tomato flavor
- red cherry, standard tomato flavor
- red cherry, sweet flavor
- large dark red cherry, tough-skinned, standard tomato flavor
- large orange-red cherry, soft-skinned, sweet

[William Schlegel]

With temperatures currently around 90F during the day and 50 to 60 F at night I'm curious to see if any lines do or don't have difficulty setting fruit through the heat wave. It's possible with the nights still cool it won't make much difference.

[Steph S]

I had a lot of days in the greenhouse with highs 90+ and lows in the 60's this July.  I did have blossom drops but I had some sets too.  Ended up with some crosses looking at the heat tolerance as a desired trait, but TBH it's impossible to account for the microclimate around a flower cluster with temperature reading in the shade.   Still if they drop less, it's a sign of some sort we hope.

It was really noticeable, the flush of fruit growing when temperatures dropped to the 80's for a day.  Also got a flush after a 90+ day when I gave them some lime slurry and a top up of an inch or two of potting mix.   Maybe just the effect of keeping the soil cooler/ covering exposed roots?

This week our highs are not quite getting to 70, and that seems to have stalled the fruit growing action again.

We're having a weird year...