Zeedman
Garden Master
The fact that tomatoes do not suffer from inbreeding depression, should not IMO be misconstrued to imply that they could not be improved via hybridization. (And this coming from someone who generally dislikes hybrids.)
As you probably suspected, @digitS' , I do have Carol's book, and consider it to be the best introduction to plant breeding for amateurs. She provides a lot of good general breeding info, and in-depth info about several species. I still have post-it notes attached to some of the pages I found most useful... but as of yet, I've only lightly dabbled in breeding. That may change when I retire in a few years, if my health holds up.
I certainly would not wish to disagree with Carol, but I have to confess that the statement you quoted has me puzzled. As @seedcorn mentioned, there are both dominant & recessive genes. In a stable homozygous variety, the recessive genes can only be expressed because they are paired with another recessive. Different varieties will have different dominant & recessive genes. When you cross two varieties, genes which were present as both dominant & recessive in the parents will contribute one of each to the F1 generation - and since the dominant genes will be expressed, the F1 will show more dominant traits than either parent. One would think that this higher number of dominant traits could produce a stronger plant... hence, "hybrid vigor". I have actually used that concept to reduce the incidence of crosses in my seedlings; if one plant is noticeably more vigorous than the rest of the population, I destroy it. I know this policy flies in the face of conventional wisdom, which recommends that you save seed from the strongest plant... but I am trying to preserve varieties as they are, not breed new ones.
It is also worth mentioning that just because a trait is dominant doesn't automatically make it desirable. Most of the tomato crosses I've seen, while very vigorous plants, had smaller fruit of poor quality. Often the recessive traits are what makes a particular vegetable enjoyable. Sweet corn is a great example (although corn genetics are more complicated).
(added emphasis mine) That was the reason that in the past, so many open-pollinated varieties were developed in publicly-funded breeding programs at land-grant colleges... back in the days when they served the public good. Open-pollinated varieties are still being bred, and the rights of the breeder are protected by the PVP patent program. It is easier & more profitable, though, for a company to protect hybrids, since saving seed that is true-to-type is virtually impossible & new seed must be purchased each year.
@digitS' , Carol Deppe has another quote that I often find useful in discussion:
“To save seeds is to complete the circle. When we save seeds, we are plant breeders, choosing which germplasm to perpetuate.”
That quote is from another of Carol's books, "The Resilient Gardener, Food Production and Self Reliance in Uncertain Times", but I know she had a similar quote in "Breed Your Own Vegetable Varieties"... that all seed saving is breeding, regardless of our intentions.
Steve
