But back to your original point on the need for a new vision of
genetics. When you look at what people are actually breeding **for**
in modern breeding programs, it is often to find genetic
compensations for managerial misjudgements.
*For example, there are people breeding for tolerance to corn
rootworm, a pest which only becomes a problem if we insist on growing
corn after corn. Corn followed by other crops does not have this
problem; it is a non issue.
*Similarly, alfalfa weevil is reportedly a significant problem in
some areas, and is the focus of breeding and chemical use, but it
becomes a problem is one simply must grow alfalfa alone, rather than
in mixture with grasses.
*Why has breeding for winterhardiness in alfalfa become a sink
for forage breeding resources? Because we insist on cutting alfalfa
3- 4X/year instead of 2-3X/year, in near monoculture without the
physical and nutritional buffering of a significant grass
component, and because we insist on growing alfalfa well outside it's
zone of adaptation, in regions subject to frequent hazardous
overwintering conditions. It could be argued that this expansion (in
Ontario at least) has been exacerbated by the long standing
provincial policy (just recently revoked) of heavily subsidizing
installation of tile drainage.
*Why is resistance to fungal pathogens a priority for wheat
breeders in the EEC? Because they are into ICM, a technology which
involves very high tiller densities, a heavily shaded lower canopy,
an environment simply ripe for fungal growth, heavy use of
fungicides, and a superb selection environment for the evolution of
resistance. I have often wondered if ICM was not, in fact, a "make-
work" plan for underemployed wheat breeders?
Nuf said. The point is, we are expending enormous amounts of
breeding resources pursuing problems which we have created ourselves,
by the way we choose to grow/manage crops, to say nothing of the
potential stimulatory effect on selection pressure that comes from
growing vast acreages of a single solitary genotype.
In a briefly optimistic moment, we argued in a recent book
chapter that breeders of the sustainable future may, in fact,
function not be releasing new cultivars, but rather, by releasing
wide populations containing a broad range of genetic adaptation which
could be **bred**, in situ, on each individual farm for adaptation to
the particular stress mileau pertaining on the farm. When we no
longer have access to the resources to homogenize the growing
environment, natural heterogeneity in stressors will re-exert itself,
which will reduce the adaptiveness of regionally bred genotypes.
The implications of wide- versus narrow-recommendation domains,
for breeding, extension, and research in general, are profound.
Enough for now. Ann
ACLARK@crop.uoguelph.ca
Dr. E. Ann Clark
Associate Professor
Crop Science
University of Guelph
Guelph, ON N1G 2W1
Phone: 519-824-4120 Ext. 2508
FAX: 519 763-8933