> With corn crossing is fairly easy, but how does it work with wheat?
Crossing is a lot harder with crops like beans, wheat, soybeans, but selfing
is a lot easier (just grow the crop). The crossed population segregates, in
the course of several generations, into a mixture of pure lines.
> Two factors maintain these varieties: the incredibile reserve
> of genetic variety farmers possess and conserve (with know help
> from anybody) and the continual experimentation and selections
> by farmers from that variety (one again, with no support).
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. Different species
have different rates of mutation and sexual recombination, but in general,
these processes that create diversity operate more slowly than the breeding
enterprise in self-pollinated crops. Human plant breeders keep creating
diversity by causing sexual recombination, allowing continuing progress.
It is difficult for amateur breeders to make crosses in soybeans or wheat,
since one must dissect the flower bud to do it. One approach is to have
some agency or organization make the crosses and increase the progeny in
bulk for one or two generations. Then the F2 or F3 bulk is distributed to
amateur breeders, who perform selection at their unique sites, on the
segregating material. Even a half dozen F2 seeds can produce thousands of
distinctive pure-lines after segregation. Some of these might be just what
you are looking for on your farm. So the farmer-breeder obtains his
customized "land-race" and doesn't have to mess with tweezers and a
magnifying glass.
> There is a lot of hype about 'modern plant breeding' and now
> 'biotechnology' as being what has 'fed the world' over the
> past decades as we grew to 6 billion. But it seems to me this
> activity by farmers that has maintained the viability of our
> crops all over the world is far more important to our food
> security, past and future, than any systematic breeding or
> genetic engineering ever has or will be.
I think a lot of people would dispute this. I have heard that Norman
Borlaug is practically worshipped in India for is work with dwarf rice. I
know that the improved rice varieties turned Colombia from a net rice
importer to a strong rice exporting country. I am less familiar with the
wheat story of the green revolution, but it is probably a big success too.
Most of the green revolution work was done by public-sector breeders. I
think it has been a clear success.
Dale
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