RA 00110.pdf - OAR@ICRISAT

does not differ from that in a medium-height, 90-day
Souna (Dancette 1983). The G A M material proved
to be very susceptible to mildew with poor grain
formation.
Use of Hybrid Vigor
Since early in the program, several varietal selections
(F 1 hybrids, synthetics) were made in Senegal
and Niger to exploit hybrid vigor. In Senegal, yield
advantages of 40-60% were obtained from F 1 s and
synthetics from local populations.
The best combinations were those including one
line with good tillering habit and the other with high
grain mass per head (Etasse 1970). In Niger, topcrosses
between dwarf S 2 lines and local varieties
were tested in 1975; 3/4 Souna 74-28-1 x CIVT gave
the highest yield, 143% of the control (Chantereau
and Etasse 1976), but the program could not be
continued without locally adapted male-sterile lines.
The G A M program, which took over varietal
breeding from I R A T in Senegal, planned to use F,
hybrids derived from A 1 and A 2 cytoplasm in the
second phase of the project (Bilquez 1975).
New lines with better adaptation to local conditions
were selected from crosses with 23-D2-A1 and
239-D2-A2, but the initial hybrids were completely
destroyed by mildew. The production and testing of
F, hybrids was soon replaced by the use of synthetics.
The material from this program was incorporated
in the ICRISAT program in Senegal for
further breeding work (Gupta 1984).
At the ICRISAT Sahelian Center in Sadore,
Niger, exploratory research was conducted on hybrids.
During the 1984 season, test hybrids were
relatively early with reduced height and head length,
and good tillering. They outyielded the improved
varieties under low rainfall conditions (250 mm in
1984).
A study on crosses between wild and cultivated
pearl millets revealed a system of male sterility different
from the A 1 , A 2 , and A 3 systems (Marchais
and Pernes 1985).
Future Trends
The different research programs should be more
closely integrated in the future. Often 80-90% of the
farmers do not have adequate equipment; soil cultivation
and thinning are often not carried out, and
weeding operations are limited by time. These problems
should not be overlooked by breeding programs.
This does not mean that varieties should be
selected to suit poor cultural practices, but rather
should be capable of performing well compared to
local cultivars under existing conditions, and to outyield
them under improved conditions.
The varietal structure (population, composite,
synthetic, or hybrid) that is adopted depends primarily
on the level of development in each country.
Given the low purchasing power and technological
levels prevailing in the region, open-pollinated varieties
(populations, composites, and synthetics) should
be retained, since they adapt more easily to traditional
cultural practices than hybrids. Hybrid breeding
should not, however, be abandoned, since
hybrids could be useful for certain locations in the
future.
Variety Breeding
Breeding work should focus on:
• diversification of the genetic base in each country
through collections, and introductions from other
centers of diversity (India, East Africa, northwestern
Africa). Research on the use of wild relatives
will determine their contribution to the
improvement of local cultivars.
• use of the collected material to select better local
cultivars, and crosses between varieties of different
origin with complementary characteristics.
Importance should be given to yield components
(head length, grain size, and tillering). The creation
of composites by recombining superior F 2
lines should provide, for the short term, better
material than local cultivars. Lines selected from
different groups of early material derived from
these crosses and populations can be used to form
synthetics adapted to different climatic zones.
In the breeding program for a better grain/straw
ratio, selection of the local 3/4 population should be
continued to improve the grain mass per head as well
as smut and mildew resistance. Short-stemmed (1.8-
2.5 m) varieties should be adequate given the local
technological capacity. The importance of straw
should not, however, be underestimated if crop and
livestock production are integrated.
Drought
Resistance
An important aspect of the breeding program is
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