Thread: hybrid seeds
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Old June 15, 2009   #11
travis
Tomatovillian™
 
Join Date: Jan 2006
Location: Evansville, IN
Posts: 2,984
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A couple of things.

"The answer is that Sun Gold seeds probably take 2 years to produce. Let's say this year I grow Sungold Parents A, B, C, and D. I have folks out there hand-pollinating A to B, and C to D. So now I've got A+B and C+D. Two hybrids. Next year I will grow those two hybrids and have workers hand-pollinate AB hybrid with CD hybrid and I get F1 seeds which are essentially ABCD. Those seeds which are a hybrid of two hybrids are then sold as Sun Gold F1."

I don't think that would work. When you cross 2 hybrids, with each being 100% heterozygotous as they would be in the description given above, you will not get 100% identical genetics in the F1 seed. Therefore, even in complex hybrids, the parents must be homozygotous true breeding lines, that is they must be open pollinated to yield an F1 cross that expresses 100% identical genetics in all the seeds.

"Now, if you as the consumer grow your Jet Star or Sweet Quartz F1 seeds and then decide to save seeds out of the resulting fruit, well that's the 2nd filial generation or F2 seeds. This is where things get interesting. Now, you are going to get a genetic jumble, a mixture of the traits of the two original A and B parents. No two plants will be identical. You'll get different fruit sizes and shapes, colors, plant types, different foliage types, etc. Some plants will be healthier than others. Some will have good tasting tomatoes, some awful. And few will be 100% identical to the F1 (A+B) hybrid. Some folks say you can get about 95% of the way there depending on the parents."

If both parents are 100% homozygotous true breeding lines, then the F1 will be 100% heterozygotous and the F2 will be 50/50 heterozygotous/homozygotous. So, I don't think it's possible to get "95% of the way there" except in appearance, and then, as Feldon points out, "depending on the parents," ie: only if the 2 parents are nearly identical to begin with. For example, a tomato like Plum Regal has two nearly identical parents with the significant differences being in the degree of elongation of the fruit and one or two disease resistances. Therefore, with hybrids where both parents have characteristics that are nearly identical with regard to fruit size, fruit color, leaf form and all the other dominant traits,the F2 fruit and leaf form may look "95% identical" but the genetics still will be 50/50, and it will take several generations thereafter to get 95% stable (identical).
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