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Old February 5, 2017   #6
bower
Tomatovillian™
 
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Join Date: Feb 2012
Location: Newfoundland, Canada
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Technically the frequency of finding three recessives would be:
1/4 X 1/4 X 1/4 which is one in 64 plants.
Compare it is only 1/4 X 1/4 or one in 16 plants for two recessives. 24 plants would be certainly enough for this, but not close to the expected frequency for three.

Besides the workaround of looking for the third recessive in F3, or crossing two F2's that have the desired three traits between them, there is another option.
The handy thing about PL is that you'll know whether you have it at the seedling stage. Color traits you'll have to wait the months until you have ripe fruit, to find out what you got.
If you wanted to be certain to get all three traits in the F2, you could start four times 24 seeds, and only grow the PL ones, should be about 24 if you grow 96 seedlings.
The other option is also pretty good, to select the color traits in the F2, that is save lots of seeds from your GWR which you'll certainly get with 24 plants ( and maybe get more than one, so save seeds from all of them to make sure your PL allele is in the batch). Then the following season, start lots of seeds and once the leaves are out you'll know which ones are PL to keep.
The chances of finding the third recessive in F3 are actually quite good, because half the plants are expected to be heterozygous, that is RL/pl so they look RL but the pl allele is hidden there.
Choosing to select for color traits in F2 makes the most sense, since it's months of work to make the selection vs weeks to find a PL or not.
Also if you start ten F3 seedlings from one F2 and you don't find any PL, you can be pretty sure the allele isn't in that line so try another one.

I think you'll have an exciting year with 24 F2's from this cross. You'll have just about every color imaginable: yellow or white, pink or red, purple-black or brown-black, or green when ripe. I hope you post some pix of your favorites!
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