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sistance, ~etc. is obtained in one year which
never could be acquired at a single location.
This nursery is a tremendous help
in identifying germ plasm with resistance to
a broad spectrum of diseases. It also is
extremely useful in maintaining a strict vigilance
for new races of rust and other diseases.
With this wide spread range of activities
spearheaded by central program staff, varieties
can be developed in a matter of a few
years for almost any set of conditions. About
2,000 crosses among highly selected, widely
different, elite materials are made each year
in Mexico. After an initial screening, the segregating
progenies from the crosses flow out
to all cooperators. The best materials are returned
along with other segregating lines
from crosses made by cooperating national
scientists. Thus these far flung efforts become
a single network of variety factories.
The CIMMYT-Mexican semi-dwarf wheat
varieties, which extended the Green Revolution
to India and Pakistan, have probably reached
their upper limit in acreage. They are rapidly
being replaced by their derivatives with more
suitable qualitative characters for the region
concerned, and with a still broader type of
disease resistance. Cooperative breeding programs
in Argentina, Brazil and North Afriea
have produced varieties with resistance to a
wider spectrum of diseases including the
Septoria, Fusarium and powdery mildew, which
often cause devastating losses in these areas
in years of high rainfall. High yielding varieties
developed from a cross of Sonora x Klein
Rendidor -an Argentinian variety- are being
multiplied for distribution in North Africa and
Argentina where they appear to be superior to
all other varieties in both yield and resistance
to prevalent diseases.
AlthQugh CIMMYT's major effort has been
devoted to the spring bread wheat types, the
program in recent years has been enlarged
to include the winter wheats, durums and triticales.
A program for the blending of the winter
and spring wheat germ plasm-complexes has
been established in cooperation with the University
of California at Davis and with the
Oregon State Agricultural Experiment Station
at Corvalis. This new broad-based program
financed in part by the Rockefeller Foundation
is aimed at the development of new high
yielding varieties for the high plateau region
of Turkey and the southern-Euro-Asian winter
wheat belt.
The Durum wheats are in great demand as
a basic food grain in North Africa and for the
manufacture of maccaroni type products. In
order to prevent these types from being replaced
by the higher yielding spring bread
wheat varieties, the CIMMYT breeders have
greatly strengthened their efforts in the development
of semi-dwarf durum types comparable
to the bread wheats in yield and disease
resistance. Rapid progress is being made and
some of the new very promising varieties are
being extensively tested in North Africa.
A real break-through has been achieved in
the further improvement of the triticales. The
problems of sterility and shriveled grain have
largely been solved. This will allow the
breeders widening the germ plasm base and
concentrate heavily on the development of
high yielding varieties. The triticales show
promise of having a much higher yield potential
than any of the other small grains, and if
some of the present lines are indicative, varieties
much higher in protein quantity and
quality can be developed.
•
Wheat Production Programs
As high yielding varieties become available
for new areas, production techniques often
need to be greatly modified. Fortunately, in
India and Pakistan about 80 percent of the
production technology developed in Mexico
for the CIMMYT-Mexican varieties was applicable.
However, as the Green Revolution
moves to North Africa, Argentina, Brazil and
other regions where wheat is grown almost
exclusively under varying rainfall conditions, a
new package of production practices must be
worked out. For this reason, CIMMYT has
undertaken to help with the organization and
execution of an intensive field research program
in North Africa, (with direct support from
U.S. AID and the Ford Foundation) designed
to determine the package of practices indicated
for maximum production in the different
rainfall regimes. This includes land management,
rates, dates and manner of seeding and
kinds, rates and timing of fertilizer application.
Although it is fully realized that the ideal
package may vary from one region to another,
it is hoped that much of what is learned in
North Africa will be broadly applicable to other
dry-land areas. In any event, the experience
gained by certain CIMMYT staff members in
this region will be extremely useful in assisting
other nations with similar types of problems.
CIMMYT has a similar, less intensive, type
of corn and wheat program underway in cooperation
with the National Agricultural Technological
Institute of Argentina. This program,
supported in part by the Ford Foundation, is
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