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MrBig46 June 9, 2018 01:02 AM

Fun with tomatoes
I'm looking for fun for long autumn and winter evenings. Now my garden bloom early varieties indeterminant and determinant. I would like to do some crossing of indeterminate varieties with potato leaf with determinante varieties (Sophie's choice, Sarayev Shtambovyi or Mongolsky karlik). The sowing of this cross would be done at the beginning of October. If the pollination was successful, I would pick those with a potato leaf and try to find out if any seedlings have a growth pattern of determinant tomatoes. The place, the time, and the conditions I will certainly have.
Do I know after sowing if the crossing was successful? Should the plants be with potato leaf and also with normal?

bower June 9, 2018 08:08 AM

Hi Vladimir,

Great project!

Your F1 cross between PL variety and determinate RL will not have PL or determinate showing in the F1 generation, because both traits are recessive.
In the F2, Mendelian ratios would give you one in four PL, and one in four sp/sp determinate, and one in sixteen both PL and sp/sp. In reality the chance (probability) is a little different than Mendel's ratios, so I usually try to grow six plants to find the 1/4 recessive trait. But I have also been lucky, and found 2 recessives together with only 12 plants. And sometimes I didn't find the 1/4 recessive even with six plants - but I think this might be due to linkages in that case, as much as luck.

The nice thing about growing an F1 in the winter, is that you only need one plant and one fruit (or more) to get your F2 seeds for the next season.
It is more challenging to grow an F2 indoors because you need more plants.

Also, in crosses between a determinate and indeterminate, you end up with a variety of growth habits where sp/sp "determinate" trait is reckoned as the forming of a terminal cluster and fewer than three leaves between terminating clusters. So you will have a variety of "semi-determinate" types in there as well, some of which can be quite tall instead of terminating quickly as a stable determinate does.
This would depend entirely on the parents you choose as well. I know Sophie's Choice for example is a very compact determinate where some others are taller. Likewise in your PL parent you may have a choice between taller or more compact plants, and that will affect the amount of variation in your "determinate/semi-determinate" growth habits emerging in F2, F3 etc.

The semi-determinate can be difficult or impossible to identify while the plants are still young and small. But maybe you could screen them out and only select F2 plants that are compact and terminate the main stem very soon. You would need to grow more seedlings to do that, depending on how your two parents interact on growth habit, it may be quite feasible.

Nan_PA_6b June 9, 2018 08:37 PM

Hi Vladimir,

Use the potato leaf as the mother. Take pollen from the regular leaf. If the cross is successful, the seedlings will be regular leaf in the first generation. Keep the regular leaf seedlings and throw away the potato leaf in the first generation.

In the second generation, choose potato leaf and determinate.


MrBig46 June 10, 2018 12:53 AM

And what happens when the mother will be normal leaf?

bower June 10, 2018 06:45 AM

The F1 will be normal leaf if mother or father is normal leaf, regardless.

Sometimes people choose to make the mother the PL when doing their first cross. That is only because, if the cross was not done properly and the mother plant self pollinated, you will know you made a mistake because the self pollinated plants from those seeds will be PL instead of RL.

Self pollination is not an issue if you emasculate the flowers at the right stage, when flowers are just opening and petals are still pale yellow not fully colored. It may take several days for the pistil to mature then and be ready to receive pollen. The tip becomes enlarged and sticky, and you can see that pollen is sticking to it by the bare line left after you drag it through pollen in your collector.

More common issues for failure of a cross which I have seen, the fragility of the pistil on some varieties. Some types simply make better mothers than others, maybe they are more tolerant of the "surgery" involved in making the cross. So it is worthwhile to try both plants as mothers, do several crosses on both, and some will likely take.

Nan_PA_6b June 10, 2018 09:20 AM

There will be no way to tell if you are successful if the mother is regular leaf. When a potato leaf mother gives regular leaf babies, that is success. When a regular leaf mother gives regular leaf babies, who knows? Maybe she self-pollinated.


MrBig46 June 10, 2018 03:53 PM

One more question. How will the cross mother look indereminante potato leaf, father determinant normal leaf. Is there a chance that there will be a determinant plant in the first generation?

bower June 10, 2018 05:34 PM

Hi Vladimir,
The chance of a determinate plant in the F1 generation is = zero. Indeterminate growth habit is completely dominant to the determinate.

MrBig46 June 14, 2018 01:20 AM

Bower and Nan thank you for the information. I imagined it more simply. I wanted fun for fall and winter, but it would be a lot more work for the spring and summer. And I can not feel it anymore. And the result? Eight years for me too long. On Monday I leave for a holiday in Pilsen. There I will have plenty of time to think about what tomatoes to grow, so it was also fun for me. ;)

Nan_PA_6b June 14, 2018 04:20 PM

Vladimir, if you have lights inside, you can have fun with any small tomato plants.

1. You make the cross.

2. When those tomatoes are ripe, plant the F1 seeds. You only need one good one. (Easy to grow this inside)

3. When those are ripe, plant the F2 seeds. You should plant many F2 seeds. Do this generation outside so you can grow maybe 10 or more. (More is better.) When the tomatoes are ripe, decide which one(s) you want to keep going.

4. Plant the F3 seeds. You don't need as many. (Maybe 8?) Choose the best one(s) to keep going. Repeat until you get to F8. But by the time you get F6, you will have almost a finished product.

You can get 2 or almost 3 generations a year if you grow inside with a light in winter. You can get about 8 plants in 1 gallon trade pots (about 3 liters of soil) under one light, then put aluminum foil around it so all the light is reflected back to the plant. This is the light I use:


Jeanus June 14, 2018 10:46 PM

Lots of great information thanks for asking Mr Big46, there were somethings I hadn't thought about. Or maybe forgot.;) I am going to try some breeding. I have had abysmal luck the last few years. Tomatoes not developing, catastrophic rains, and rains causing diseases ect. Just going to try breeding to see if I can do it successfully this year, just to prove concept.

MrBig46 June 16, 2018 03:59 AM

Nan and Bower,
I do not want to shine and I can not. Tomato seedlings may only be grown in the bedroom and I must be glad (wife).
ad 2) I really need only one F1 plant? I know all of them will be indeterminate and normal. Is it really arbitrary which I choose?

Nan_PA_6b June 16, 2018 12:09 PM

You are right, Vladimir; your wife must be more important than your tomatoes.

Every F1 is the same. But if one looks healthier, bigger, etc., choose that one.


bower June 16, 2018 04:45 PM

Yes, to get seed from the F1 you only need one plant - if both parents are stable OP, every F1 will be identical genetically, so there's no need for extra F1 plants unless you are testing out the F1 itself.

The usual advice is to collect several hundred F2 seeds. But that may also depend on your plans and needs. I often end up with hundreds of seeds that will never be grown out - I don't have the capability to grow hundreds of plants per generation, and in addition, if I can find what I'm looking for with ten plants, well the rest of the seeds will be waiting a long time for their chance to be grown here. :lol: It's nice to have some seeds as backup, in case I needed to start over for some reason, but in most cases the seeds from one fruit of the F1 would be more than enough.

MrBig46 June 30, 2018 11:36 PM

Yesterday I sowed the seeds of four varieties pořebných for breeding. Mother- Stupické polní rané. Potential fathers- Sarayev shtanbovyi, Sophie´s choice and Mongolskyi karlik.

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