RA 00110.pdf - OAR@ICRISAT

Moderator's Overview
Improvement Through Plant Breeding
D . J . Andrews 1
It is a pleasure for me to chair this important session
in which we have some outstanding speakers to
bring us up to date on progress in breeding pearl
millet.
However, I would first like to mention some principles
which are important for the continued genetic
improvement of pearl millet, and then review some
important events.
When planning breeding activities, it is necessary
to apply basic principles:
1. Analyze production constraints from which clear
and realistic breeding objectives can be formulated.
2. Acquire and update regularly relevant genetic
diversity.
3. Obtain as much direct evidence (if not available,
the best indirect evidence) on the genetic nature
of important traits.
4. Use breeding strategies consistent with the preceding
three points that are within your budget.
5. Carefully choose test environments which consistently
permit the best identification of the
desired genotypes.
It should also be clear that in pearl millet, the main
endeavors should be directed primarily to those
environments where other cereals cannot compete.
These are generally characterized by short growing
seasons; sandy, nutrient-deficient soils; and low,
erratic rainfall coupled with high temperatures leading
to high evapotranspiration rates. There are
exceptions of course, but we should not let them
divert us from our principal task—breeding improved
cultivars for the difficult environments I have
described.
Lest you misunderstand me, I think that high yield
potential is important in such environments.
Crop production increases of genetic origin are
usually obtained steadily, inch by inch, by diligent
research over the years. A 1% average yield increase
in the major world crops is regarded as good. I think
we have done better than this in pearl millet on the
Indian subcontinent, and should make it known
how this was done. There are more complex limitations
to production in Africa, particularly in West
Africa, but the route is clearer because of the demonstrated
yield increases in Asia.
While there has been a basic gradual improvement,
two important events have influenced yield
gains in Asia, and already these are in gestation in
Africa.
The first event was the breeding and adoption by
farmers of hybrids in India. This gave us a hint of the
yield potential of the crop, but drew our attention to
the instability of individual hybrids as a result of
nondurable disease resistance.
The second event was the use of recurrent selection
in populations as a breeding strategy to produce
increasingly higher-yielding, disease-resistant varieties
and pollen parents. Recent A I C M I P test results
show that new varieties from the later cycles of populations
are about 15% better than WC-C75, which in
turn was 16% better than local varieties in 140 all-
India tests. New hybrids are apparently even higher
yielding: two 1986 releases are yielding about 25%
more than WC-C75 in A I C M I P tests.
The application of conventional breeding techniques
will no doubt continue to increase yields of
hybrids and varieties, but eventually returns will
diminish and something else must be done. Before
this time, we must be ready with new techniques.
The key will be increased growth rates—and this
brings biotechnology to mind. But I think there is a
more immediate way: the use of germplasm from
wild and related species in breeding programs.
Research at ICRISAT showed derivatives of controlled
crosses between shibras and cultivated lines
produced up to 40% higher growth rates. Dr. Hanna
has indicated gains of a similar magnitude can be
expected using wild pearl millet (monodii) sources.
Additionally, there is the attractive possibility of
fixing heterosis through apomixis. I believe that we
have only just begun to tap the potential of pearl
millet. But we need now to turn to the reviews of
recent breeding research accomplishments, and use
them to develop our future strategies.
I. Plant Breeder, 279, Plant Sciences, East Campus, UNL, Lincoln, NE 68583-0910, USA.
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