RA 00110.pdf - OAR@ICRISAT

• Well adapted, early-maturity, local materials are
already available in local land races for use as
breeding material. Primary reliance on exotic
materials for early maturity may not be necessary.
• In tests of new materials, breeders must employ
local control cultivars which correspond to the
maturity of the new cultivars being tested if valid
comparisons are to be made.
• Farmers are not irrationally attached to their
traditional cereal cultivars. Rather they are willing,
indeed anxious, to experiment with and
adopt new cultivars which they evaluate as being
better suited to their needs.
Assigning Weights to Research on Millets of
Various Maturity Groups
Most cereal improvement programs in the WASAT
have responded to the growing demand for earliermaturing
cultivars by accenting this characteristic in
their selection and breeding. Methods to establish
priorities among maturity groups, however, are
poorly defined. The ICRISAT Millet Improvement
Program in Burkina Faso, for example, focuses on
breeding two cultivar groups for the Sudan savanna
transition zone: photoperiod-sensitive, full-season
cultivars which mature in about 120-140 d; and
photoperiod-low-sensitive or photoperiod-insensitive,
short-duration cultivars (80-110 d) for late sowing
conditions. While it is difficult to define with precision,
the current allocation of program resources is
approximately three-quarters to long- and onequarter
to short-cycle materials.
One way to test whether this is an appropriate
balance is to compare the allocation of research
resources with the maximum potential area on
which cultivars of various maturities could be adopted
as direct replacements for locals while holding planting
patterns (timing, area, etc.) unchanged. In Burkina
Faso, outside of the Sahel there is very limited
first planting adoption potential for new millet cultivars
with cycle lengths of less than 110 d (less than
15% of millet area is available in the Sudan and less
than 5% in the northern Guinea savanna) (Fig. 1).
To reach adoption potential of 50% of first planting
area, cultivars with maturity lengths of 115-135 d are
appropriate in the Sahel, 130-140 d in the Sudan
savanna, and cultivars > 165 d are required in the
northern Guinean zone. As material for replanting,
the potential for early-maturing millets is only
slightly more important, and is generally less than
15% of the area in the Sahel and Sudan savanna.
Thus the total adoption potential of 80-110 d cultivars
in the Sudan savanna villages varied between
about 17% in 1981 to about 22% in 1982. According
to these studies the data suggest a nearly correct
allocation of resources in the Burkina Faso millet
program to the short-maturity group.
Short-maturity cultivars would be grown more if
cropping systems were adopted which use relay
cropping or delayed first plantings to allow greater
soil preparation. But to justify allocating more
resources to breeding such cultivars, researchers
should first clearly define the alternative cropping
systems for these cultivars, and evaluate the likelihood
of these systems being adopted in the foreseeable
future.
The timing of farmers' plantings has another
important implication in setting millet improvement
objectives. Labor-intensive, hand-planting methods
and the irregular distribution of early-season rainfall
combine to extend major first plantings of millet
over a period of about 45 d in the Sahel zone to more
than 60 d in the northern Guinean Zone. Under these
circumstances photoperiod-insensitive cultivars with
short planting windows are poorly suited for broad
adoption. An important degree of photoperiod sensitivity,
which lends increased planting date flexibility,
is necessary to expand the adoption potential of
new cultivars.
Comparative Management Responsiveness
among Crops and Cultivars
The different responses of major cereals to enhanced
soil fertility and improved soil tillage is well documented.
The implications of such differences to crop
improvement strategies in diversified cropping systems
and input scarcity is less well recognized.
Technical Response and Returns to Fertilizer
The experimental results found by the Institut de
Recherches Agronomiques Tropicales et des Cultures
Vivrieres (IRAT) in Burkina Faso is typical of
the broad differences in response to fertilizer among
cereals (Bonnal 1983). During 1978-1982 in two
locations, 100 kg cotton complex fertilizer (14:23:15)
plus 50 kg ha -1 urea (47% N) gave a grain-yield
increment that was highest for sorghum (760 kg
ha -1 ), and substantially lower for millet (230 kg
ha -1 ). Similar crop differentials have been observed
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