RA 00110.pdf - OAR@ICRISAT

Discussion
Squire's paper drew on data from India, West
Africa, and controlled environment conditions in
the UK, and provided a review of the relationships be
tween many of the important environmental variables,
and pearl millet growth.
The discussion centered around the usefulness
and application of these data, on the simple model
presented, and the general acceptance of the root
growth data and its measurement. The overall opinion
was that the model was flexible, but the speaker
admitted that more good data were required, particularly
in relation to roots. The importance of saturation
deficit was not challenged, and the speaker
agreed that traditional methods for the measurements
of roots and soil-water such as potentiometers
and the neutron probe were probably better than
sophisticated tracer methods.
Matlon's paper clearly showed that interpretation
of experiment station data, generated utilizing many
inputs not available to West African farmers, should
be done cautiously. Similar caution should be
observed when comparing data from the three climatic
zones, the Sahel, the Sudanian, and the
Northern Guinean Zones. The discussion centered
around these two issues.
The poor response of new cultivars compared to
locals under both low- and higher-input conditions
on farmers' fields was clearly disturbing to the
audience, but the consensus, substantiated by the
data presented, was that this is a problem, and
ICRISAT should concentrate on solving it. There
was some disagreement about the statement that
very early-maturing cultivars will have no impact
unless management practices change.
There was general acceptance that the primary
goal in the Sahel is to increase the responsiveness of
new cultivars to improved management, but that in
the other two zones, the goal is to improve yield
stability. The group endorsed a comment that more
emphasis should be put on soil and water management
in West Africa.
Fussell's paper provided potential solutions to the
problems outlined in Matlon's paper. Little progress
would be made in increasing grain yield unless fertilizer
is used, particularly phosphate. This was accepted
with the proviso that the importance of water and
soil management should not be completely dismissed.
Gautam's paper described the management practices
to increase and stablize production in India.
The discussion centered on matching plant populations
to different environments, and the placement
and timing of fertilizer applications.
Bidinger's paper, which acknowledged that plants
have no immunity to environmental stresses, presented
a physiological approach to breeding for
'resistance' to such stresses. A stepwise approach,
using data from Niger and India, was used to illustrate
the approach. Poor crop establishment and
inadequate grain filling were used as examples. The
discussion centered on whether the approach was
over simplified, and whether there was a danger in
examining growth stages or stress periods separately.
Bidinger argued that understanding each stage
separately and clearly defining the problems in a
particular climatic zone was necessary. It was agreed
that stress incurred in the seedling stage, provided
the seedling survived, could be advantageous to a
plant subjected to stress in the later stages of
development.
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