RA 00048.pdf - OAR@ICRISAT

Session 6
Production Technology
Discussion
Norman
ICRISAT is to be congratulated for taking a
leadership role in intercropping work thereby
helping to make research in this area a respectable
occupation for scientists. Dr. Willey has
clearly shown the possible advantages of intercropping
in increasing land productivity. Have
you looked at the potential of intercropping to
increase the productivity of labor at critical
bottleneck periods? In West Africa, intercropping
is commonly practiced by farmers with labor
rather than land limitations. Productivity of their
labor input during the critical weeding period is
increased by growing crops in mixtures rather
than as sole stands. (Factors contributing to this
are increments in gross yield per hectare through
growing the crops together, i.e., LER 1—and
higher stands per ha—i.e., millet plus sorghum
compared with millet or sorghum sole crops
—which may reduce weed problems). The
potential for improved techniques for intercrops
in labor scarce areas, particularly for farmers
using hand tools, is great. This is especially the
case when yields of improved technologies for
sole sorghum are not spectacular thereby often
resulting in a decrease in the return per unit of
labor input during the critical period compared
with the traditional sorghum technology. A complementary
intercrop would in such interaction
help increase the return per unit area and per unit
of labor thereby helping the adoption of improved
yield-increasing sorghum technologies in
labor scarce areas. This has in fact happened in
parts of northern Nigeria where long cycle
SK5912 sorghum is often grown by farmers in
mixtures with short cycle traditional millet. Incidentally
some of Andrew's work indicates that
animal traction is possible with intercrops. In
order to get the labor factor into designing and
analyzing improved technological packages, it is
necessary to pay increasing attention to work at
the farm level.
Willey
We have not specifically looked at intercropping
productivity per unit of labor input, though we
are aware of your work on this aspect. As with
any cropping system, it is obviously logical and
useful to examine productivity against any resource
that is particularly limiting. For most
operations (e.g., cultivations) labor inputs are
unlikely to be greater for one hectare of intercropping
than for one hectare of sole cropping,
and for important weeding operations they can
be less. The higher productivity per unit area
from intercropping will thus often give higher
productivity per unit of labor input.
House
In terms of yield, varieties developed at ICRISAT
Center have not really contributed as compared
to locals when both are grown on farmers' fields
in drought prone areas of West Africa. We are
making an effort to use heterosis in order to
obtain an increase in yields. There is interest in
hybrids but the available information suggests
that in dry areas this is not an easy job. We are
looking at the possibility of sorghum synthetics.
The West African types are very open-headed
and natural outcrossing may be sufficient. Bhola
Nath at ICRISAT is beginning to use ms 3 and ms,
to build a composite that a farmer can use
with the sterility remaining in the population. We
are also interested in what opportunities may
come from apomixis.
Balasubramanian
Dr. Willey made an interesting observation that
nitrogen fixation of groundnut in intercropping
with sorghum was reduced. Was it due to
reduction in plant size or due to fewer nodules?
Willey
Plant size, nodule number, nodule weight, and
fixation rate can all be reduced in intercropping
but the point I was making was that our
microbiologists have found that even where
plant size is not reduced, fixation rate often is.
Current evidence is that fixation is preferentially
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