Hi TomHill,
As you mentioned, many vegetable crops are monoecious and commonly self pollinated. Most, like peppers have relatively little diversity within any given population. Such highly uniform, self pollinated species can usually be maintained with small populations without much loss of traits. Curcubits (squash, melons, cukes etc.) are similar and are unlikely to display 'inbreeding depression' even after multiple selfed generations. Beans are easy to maintain with very small seedbatches, but corn needs to be grown in huge populations to avoid decline.
If your definition of success is a line that maintained traits over many generations then I have a 'success' to tell you about using my method. I'm not sure exactly, but I'd say my Cherry Bomb is somewhere around F20-22 now, with never an incross at any time. As we know, any given seed can only have two P's even if multiple males were used in the cross, as I did starting with the first generation of CB (somewhere between '77-'79). In the early generations, I did apply a fair amount of pressure, growing out large populations (often in 'waves' if I didn't have enough space) and using only select plants. I gradually included more plants as the number of suitable ones increased. I've heard stories about other 'IBL's' in existence, but have yet to grow out a batch of seeds with as many similar traits as CB. Local growers who've grown CB report the same.
Tom, you know this, but for those who are following along; outbreeding (Alard said 'outcrossing') and inbreeding are two terms used by plant breeders to distinguish the methods used to breed two categories of plants which are not so much distinguished by some taxonomical feature as by the methods used to breed them. The main difference between outbreeding plant species and inbreeding ones is the population size needed to maintain them. Inbreeding species can be as easily maintained with about one fifth the population size as outbreeding ones.
I didn't mean to indicate that I didn't agree with successive SPxSS generations, because after all, each seed has only two parents, eh? Unless I'm still missing something, the only real difference we're talking about is whether to progeny test, back up and replant those seedbatches that produce more suitable plants (in larger populations), or just include more staminate parents and seeds from multiple moms in a grow. While I more often follow the latter scheme, I have had to apply the greater selective pressure of progeny testing (even with males) two or three times. But, it's a method I've used only when it's obviously the only way to get the traits I wanted. I'm throwing out the word 'obviously' in a pretty cavalier way, but I can say it took two or three grows to even determine that it was a path I needed to follow. A discussion about the why's would be a real can of worms and I doubt would be of much interest to more than a very few.
As you mentioned, many vegetable crops are monoecious and commonly self pollinated. Most, like peppers have relatively little diversity within any given population. Such highly uniform, self pollinated species can usually be maintained with small populations without much loss of traits. Curcubits (squash, melons, cukes etc.) are similar and are unlikely to display 'inbreeding depression' even after multiple selfed generations. Beans are easy to maintain with very small seedbatches, but corn needs to be grown in huge populations to avoid decline.
If your definition of success is a line that maintained traits over many generations then I have a 'success' to tell you about using my method. I'm not sure exactly, but I'd say my Cherry Bomb is somewhere around F20-22 now, with never an incross at any time. As we know, any given seed can only have two P's even if multiple males were used in the cross, as I did starting with the first generation of CB (somewhere between '77-'79). In the early generations, I did apply a fair amount of pressure, growing out large populations (often in 'waves' if I didn't have enough space) and using only select plants. I gradually included more plants as the number of suitable ones increased. I've heard stories about other 'IBL's' in existence, but have yet to grow out a batch of seeds with as many similar traits as CB. Local growers who've grown CB report the same.
Tom, you know this, but for those who are following along; outbreeding (Alard said 'outcrossing') and inbreeding are two terms used by plant breeders to distinguish the methods used to breed two categories of plants which are not so much distinguished by some taxonomical feature as by the methods used to breed them. The main difference between outbreeding plant species and inbreeding ones is the population size needed to maintain them. Inbreeding species can be as easily maintained with about one fifth the population size as outbreeding ones.
I didn't mean to indicate that I didn't agree with successive SPxSS generations, because after all, each seed has only two parents, eh? Unless I'm still missing something, the only real difference we're talking about is whether to progeny test, back up and replant those seedbatches that produce more suitable plants (in larger populations), or just include more staminate parents and seeds from multiple moms in a grow. While I more often follow the latter scheme, I have had to apply the greater selective pressure of progeny testing (even with males) two or three times. But, it's a method I've used only when it's obviously the only way to get the traits I wanted. I'm throwing out the word 'obviously' in a pretty cavalier way, but I can say it took two or three grows to even determine that it was a path I needed to follow. A discussion about the why's would be a real can of worms and I doubt would be of much interest to more than a very few.
,,,
