Quote:
Originally Posted by Fred Hempel
Disease resistance is very tricky, because there are cases where being homozygous for a resistance gene will result in a "cost" (less vigor, etc.). However, there must also be cases where homozygous is better. That said, disease resistance stacking at many loci is probably both very difficult to achieve, and will lead to vigor costs. And it is important to note that vigor is also one general way to "fight" disease, so reducing vigor reduces general disease resistance.
One reason I think I generally see better "general" disease resistance in hybrids is because my experience tells me very clearly that plant vigor is generally enhanced in hybrids -- probably due to the genetic diversity increase in hybrids (because the two parents will have alternate forms of genes at many loci, and thus more genes and more "solutions" to problems)
I do find that OPs have better resistance in earlier generations, when they are still genetically more diverse. I have had countless examples where OPs I am developing get "weaker" over time. My general selections are based on taste, but I still always try to also select for vigor when I have a number of plants in a population with equivalent taste.
I do not choose parents specifically to be more productive, and I don't follow disease markers or "vigor" markers.
I do try to start with parents that are generally decent with regards to vigor and disease resistance. And my parental lines clearly do have some genes that have been specifically put there by other breeders. I just don't follow them molecularly. But, I assume that I select for them in the field.
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That explains a lot. In a couple of occasions, I have grown hybrids that I liked and were quite productive. However, to keep growing them I had only one vendor to buy from and they had no other seeds I was interested in. It was hard for me to justify buying a single packet of seeds along with shipping, so I just starting savings seeds. It is easy for me to get a few generations away from the original seeds, given that I grow 2 crops a year and can save seeds twice a year. But ultimately, they got to a point where their performance was so poor that I just give up on them. Thanks
Larry