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Forum area for discussing hybridizing tomatoes in technical terms and information pertinent to trait/variety specific long-term (1+ years) growout projects.

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Old November 23, 2017   #1
Labradors2
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Default F2 or F3?

I'm bumbling along, trying to capture "taste" and "dwarfism" in a bee cross. From my limited trials, it seems that taste shows up in the F2 no matter what kind of leaf or tomato shape I get .

OTOH dwarfism is proving extremely difficult to capture. Twice, I planted 16 seeds in a pot, but couldn't detect obvious dwarfs, just smaller seedlings that were a little later to germinate!

I saved seeds from the best F3 to go forward, although I only grew 6 plants. It had uniform great-tasting saladette-sized fruits, was quite productive and didn't grow excessively tall in a container.

My first question is, should I go forward with the F3 seeds next year, or try again with as many F2's as I can find space for?

My second question is will the great taste stay, or will I have problems as I proceed with more growouts?

Linda
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Old November 23, 2017   #2
bower
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Well I'm not sure, but I think the expected ratio of dwarfs would be 1/4 ?? If two genes are involved, 1/16. Crmauch posted a thread some time ago about probabilities vs the genetic ratios, so you do need to hedge your bets with more plants. Six is usually good for 1/4 - but I also have missed the recessive with six plants. If two genes are involved.. more than 16 is a good idea, not sure how many.

OTOH, If your F2 plants are not large, possibly they are carrying the gene (or genes?) for dwarf and it may still come out in the F3.

It's great that you got the taste though, even if you missed the dwarfs. Someone with more experience can tell you how easy that is to stabilize, but at least early generations I would say taste is not hard to recover, if it's there in F2 you should find it dominating the F3 and 4 as well... Just a SWAG, you may find off types in a recessive ratio - so 1/4 ish to 1/6 ish. Not sure how much this depends on the actual parents in a cross (somewhat! for sure).

One thing I have thought about doing but haven't due to space limits, is to grow F2 and F3 generations simultaneously. It would be cool to do that and really judge, is taste changing as generations go by or not. Being every season has its own limits...
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Old November 24, 2017   #3
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Yes. I was expecting to find 4 dwarfs amongst my two pots of 16 seedlings, but none were obvious dwarfs. The ratio of PL to RL was off as well as I was finding way more than 4 PL in each batch. Just goes to show that if we are doing a small sample, the statistics can be way off.

Good to know I could still get dwarfs in the F3

I think taste is the most important thing, and I like the idea of growing more F2's to judge if it has stayed the same, but maybe another year .

The other thing that has happened is that I'm sometimes getting a bit of a tough skin and I'm not sure if I can blame weather conditions for that.

Linda
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Old November 24, 2017   #4
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If RL-PL ratio is off as well, I think it's likely that your F1 also had a bee cross. So that three parents are now involved, with the third also being a PL.
That would make your F2 really an F1...
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Old November 24, 2017   #5
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You would think

However, in the chicken world people often complain that they get a very high rate of roosters when they hatch their own eggs. One would expect to get 50/50 chance to get a hen or a rooster, but I doubt that many are hatching 100 eggs at a time.... Maybe I should add that people wouldn't bother to complain if they hatched out all hens {LOL}.

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Old November 28, 2017   #6
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Linda,

There's a difference between the chance of getting a particular trait to show up and what happens when you're actually planting. On the average, you would see your dwarf trait one in four plants. But as you know when it comes to flipping a coin, you can flip a lot of times without getting "the average" outcome.

I took statistics and calculated the odds of getting a "1 in 4" trait.* While you would expect it to be seen in 4 plants, it would be within normal limits to not see the trait until the 16th plant. That means that it's not all that eyebrow-raising to not see it in 15 seedlings. You have grown 32 seedlings with no dwarf. Yes, that is eyebrow raising.

You could: 1) presume you've been unlucky and try another 16 seeds (easy to do), 2) presume something went wrong with the original cross and make the F1 cross again, or 3) bag all hope of the dwarf & concentrate on flavor in the F3. It could happen that you'd see the dwarf in F3, but don't count on it.

*(I bred lovebirds, and one set of non-blue parents gave me 15 non-blue babies. The 16th one was blue. Blue should be a 1-in-4 possibility. I calculated it out and seeing the trait in the 16th baby was really within normal limits.)

Nan
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Old November 28, 2017   #7
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Thanks Nan,

Interesting about the lovebird stats!

No, I cannot recreate the F1 again because I don't know what it was that crossed with my dwarf, but I can still do a dwarf hunt with the F2 seeds that I have. Watch me germinate 32 seeds and get a ton of dwarfs this time {LOL}. Of course I don't have to keep all the plants from that project so I'll still have lots of room for a large F3 growout

Thanks,
Linda
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Old November 28, 2017   #8
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Linda, what sort of dwarf gene does the dwarf parent have? If its the sun gene, would you see dwarfing in the seedlings under lights?

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Old November 29, 2017   #9
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It doesn't have the sun gene because the fruit are always round. Guess I'll just have to germinate a lot of my F2 seeds and hope that I get a dwarf or two......

Linda
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Old November 29, 2017   #10
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No, sorry, I meant sun-dwarf (sd) gene

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Old November 29, 2017   #11
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They aren't micro tomatoes either, but in researching sun dwarf, I came across this very interesting piece by Darren Abbey: http://the-biologist-is-in.blogspot....-tomatoes.html wherein he says the following: "The dwarf plants are distinguishable very early because the leaves remain splayed (yellow 'D's at right), while in normal plants they fold upwards at night (red 'N's at right)".

That is incredibly helpful to me .

Linda
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