RA 00048.pdf - OAR@ICRISAT

maturing crop. This situation is typified by the
sorghum/pigeonpea combination that is particularly
important in India and also occurs in East
Africa. In both these areas the sorghum is usually
regarded as the main component; in fact in India,
the traditional objective is to produce a "full" yield
of sorghum with some "additional" yield of
pigeonpea. The farmer achieves this by sowing
several rows of sorghum and only occasional
rows of pigeonpea. While this safeguards the
sorghum yield, however, it severely limits the
pigeonpea contribution and thus yield advantages
are low.
Figure 2 shows the growth patterns of an
improved sorghum/pigeonpea situation where
the pigeonpea was sown in every third row but
the population of each crop was maintained at its
full sole crop level by reducing within-row spacings.
The dry matter accumulation of intercropped
1000
800
600
400
200-
0-
100
90
80
70
6 0
50
40
30
2 0
10
0
(a)
(b)
Sole
sorghum
Sole
sorghum
Intercrop
Intercrop
sorghum
Sole
Days after sowing
Sorghum harvest
Sole pigeonpea
pigeonpea
0 20 40 6 0 80 100 120 140 160
Days from sowing
Intercrop
pigeonpea
Figure 2. la) Dry-matter production by sorghum
and pigeonpea in sole and intercrop
systems as a function of days from
sowing; lb) light interception by sole
pigeonpea, sole sorghum, and combined
intercrop as a function of days
from sowing.
sorghum was only slightly less than sole sorghum
and grain yields were similar at 4240 and 4500
kg/ha, respectively. Thus, despite the high sown
proportion of pigeonpea, an almost full yield of
sorghum was achieved by maintaining the full
sorghum population.
Figure 2 also shows that although the pigeonpea
component suffered considerable competition
during the period of sorghum growth, it
partially compensated later and was finally able to
produce a dry matter yield equivalent to 53% of
the sole crop. Moreover, because the sorghum
competition largely suppressed the early vegetative
growth of the pigeonpea, the harvest index
was increased from 2 2 % in sole cropping to 3 0 %
in intercropping; thus the intercropped pigeonpea
seed yield was a very considerable 7 2 % of the
sole crop.
It must be emphasized, however, that these
particular figures were obtained from deep Vertisols
which have a very high moisture holding
capacity and which in the Hyderabad situation
have a potential growing period of about 6
months: In this situation it is important to compare
the intercropping system with other possible
systems such as sequential or relay systems, and
such comparisons will be made in a later section.
On lighter soils, however, there is usualy little or
no opportunity for sequential or relay cropping and
although intercropped pigeonpea yields are usually
less ( 4 0 - 5 0 % of sole crop yields on Alfisols at
ICRISAT), in these situations the yield advantages
indicated for intercropping (e.g., by the LER) are
genuine yield increases over sole cropping.
Sorghum is also found intercropped with other
long-season crops. In Maharashtra state in India a
typical traditional pattern is several rows of cotton
with a strip of two to three rows of sorghum and
pigeonpea, either in separate rows or mixed
within the row. With the introduction of improved
genotypes of cotton there has been a move to
sole cropping though studies have still shown
worthwhile advantage of intercropping. Thus with
Lakshmi cotton and CSH-6 sorghum, Prithvi Raj et
al. (1972) showed intercropping yield advantages
of more than 3 0 % for row arrangements of 2
sorghum:2 cotton or 3 sorghum:2 cotton;
moreover both these intercrops gave higher
monetary returns than either sole crop.
Sorghum is also one of the cereals intercropped
with cotton in Nigeria, though the cotton cash
crop usually suffers considerable competition,
because it is relegated to much later planting than
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