You don't really lose a year of progress, because you need to go approximately 7 generations to get stable, and it doesn't really matter which generations your two recessive genes of interest get "fixed". You still have to continue to get all of the other genes homozygous.
What I described to you is my general method of looking through F2 and F3 populations. I think perhaps too much interest is often placed on getting the exact F2 you want, and too little effort is made to continue to select at the F3 generation.
There is still alot of variability at F3, and if you have saved seed from a few F2 families that are most exciting to you, the F3 can be a gold mine of new variations.
Even though I am growing in a field, and I can grow thousands of plants, I very rarely grow out more than 20 plants in the F2 generation, and my rule of thumb for my most exciting projects is usually 8-10.
I would say most often am growing out only 5 F3, but if I am looking for something that might be recessive, I might grow out 10 F3 plants (for each F2 plant that might be heterozygous for something).
Quote:
Originally Posted by katwest
Thanks Fred. Very helpful and interesting. How many F3 plants would you grow out in using your two-step strategy (does it have a name)?
I see the obvious benefit in terms of space, but you lose a year of progress so I suppose it depends whether space or time is the priority. I have a really small urban farm so space is always an issue for me - but I'm also impatient to see results.  |