>Land-race varieties of self pollinated crops, unlike corn, are mixtures of
>pure-lines, each of which breed true. Much gain is made initially by
>selection, but then gain declines to practically zero...
"Gain" in terms of increasing a given trait (yield, oil content) in a
constant environment perhpas...but as Forest Troyer said, "Adaptation is
everything - the sole driving force of evolutionary biology. Better
adaptation to the environment means higher yielding corn.." Evolution is
adaptation to a specific and changing environment and that is what farmer
breeding achieves. So really the "gain" in this sense does not decline.
But my question is how do farmer do this with self-pollinating crops? That
is why the "sistem lines" research is interesting. For example. Chiapas
is center for maize diversity. It easy to see how this diversity is
maintained and used te create further diversity by farmers. But Chiapas is
also a center of bean diversity. Every village seems to have its own bean
variety. In general in Mexico bean diversity is astounding. How is this done?
Mexico, D.F. & San Cristóbal de Las Casas, Chiapas
Tel. y FAX 525-666-73-66 (DF)
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