RA 00048.pdf - OAR@ICRISAT

a. Transfer of existing local varieties and techniques
either within or between zones in the
West African SAT. For this purpose the
collection of local sorghums should be
tested at several planting dates and at
several sites which cover the various ecological
zones. This extensive testing is required
to identify specific adaptation, pest
and disease resistance, and yield stability
under late planting—characteristics which
could be useful in a future crossing program.
b. Breeding for resistances to yield-reducing
factors such as diseases (sooty stripe, He/-
minthosporium blight, grain mold, charcoal
rot), insect pests (shoot fly. midge, aphids).
and Striga, to improve yield stability of local
varieties. This strategy basically aims for a
step-by-step approach starting from a lowinput
agriculture, on low fertility soils (being
the common situation for most sorghum
fields).
c. Breeding hybrids and pure-line varieties for
high yields under high input and high management
while screening advanced lines for
yields higher than locals even under low
input and traditional management. This
strategy is mainly based on the introduction
of exotics and screening the progeny from
exotic x local cultivars. These crosses have
received the most attention in the past few
decades, but have rarely been tested under
low management conditions and have as yet
made little impact in West African farmers'
fields.
d. Breeding for agronomic characteristics to
better fit improved varieties into existing
systems. Breeding goals may include:
—varieties with maturity cycles ranging
from very early photoperiod-insensitive
(100 days) to very late photoperiodsensitive
materials (150 days);
—greater tillering in order to allow for a
lower plant population or for compensation
of plants lost in early droughts; and
—greater compatibility with intercrops, particularly
cowpea, by changing plant structure
(for instance plants with fewer and
narrower leaves).
AGRONOMY. For many situations in West Africa
various agronomic constraints appear to be more
serious than genetic limitations of local varieties
and will need more emphasis in the future if the
merits of improved varieties are to be fully
exploited.
Since commercial inputs are expensive and
often unavailable to most farmers, the major
agronomic strategy of ICRISAT in Upper Volta and
Mali has been to exploit to a maximum the
environmental factors (soil and rainfall) and biological
factors (cropping systems, rotations, and
plant types). Results of these efforts have been
presented in several papers (Stoop et al. 1980;
Stoop and van Staveren 1981). Two key agronomic
problems are common to many parts of West
Africa, and need special attention: maintenance of
soil fertility, and erosion control. The latter, especially,
is connected with overextended farms and
the poor use of animal equipment (repeated
plowing and cropping of natural drains).
Phase 3: Preextension On-farm Studies
In many tropical countries there is a rather strict
separation between research and extension. As a
result many scientists are not actively concerned
with the adoption of their improved varieties and
technologies by farmers, and thus remain unaware
not only of farmers' constraints but also of
the possible shortcomings of their proposed
improvements. Likewise, the reasons for the
shortfall between yields realized on-station and
those under farmers' conditions are rarely critically
analyzed (ICRISAT 1981). In response to this
situation many of the International Agricultural
Research Centers have started to promote onfarm
testing in their training (CIMMYT 1978) and
outreach programs.
On-farm testing must involve more than just
placing a number of plots in farmers' fields to
evaluate and demonstrate a new variety or technique.
Rather, one can distinguish between "onfarm
trials" and "farmers' tests". The former
consists of controlled experiments managed by
researchers but located on farmers' fields under
more representative soil, disease, and pest conditions
than on a research station. The latter,
"farmers' tests", are not only situated on farmers'
land but are also managed by farmers who are
free to modify the recommendations. Such modifications
may represent points of conflict with
other elements in the farmers' operations and, as
such, are analyzed as farmer-introduced treatments.
Intensive input-output data are collected
for the test results as well as for other fields of
participating farmers in order to place the test
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