RA 00015.pdf - OAR@ICRISAT

Growth Studies in Controlled
Environments
Our field studies on growth of chickpea are being
supplemented by work in the Plant Environment
Laboratory at Reading University in England.
Under a collaborative project financed by the
Ministry of Overseas Development, R. J. Summerfield
and his colleagues have completed initial
experiments in which several cultivars were
grown to maturity in controlled environments.
With appropriate light sources, the plants closely
resembled those grown in the field in India. At
present an experiment involving different day
and night temperatures and daylengths is in
progress; this has already revealed very marked
and distinct effects of both day and night
temperatures.
Insect Pest D a m a g e
Most of the current chickpea entomology research
is concerned with Heliothis armigera
(Hub.) which is known to be the most damaging
pest of this crop throughout Asia and Africa. In
the 1976-1977 season at ICRISAT Center this
insect was again the only really important pest on
chickpea; during early growth of the plants the
larvae were found feeding on the leaves and later
they destroyed flowers and bored into the green
pods.
In an attempt to quantify the yield loss caused
by these insects on the kabuli and desi types,
plots in which the plants were sprayed with
endosulfan and from which the larger H. armigera
larvae were removed by hand were compared
with nontreated plots. The percentage of
pods damaged, number of pods harvested, and
seed yields are shown in Table 38.
Pest control gave a 55-percent increase in yield
from the kabuli type; most of this clearly resulted
from the increase in number of pods harvested.
In the desi type there was no final reduction in
pod-set in the nonsprayed plots and the small
increase in yield from pest control was associated
with the reduction in pod boring. These results
confirm earlier observations that kabuli types are
Table 38. Comparison of pod damage and yield
in chickpea cultivars under sprayed
and nonsprayed conditions at
ICRISAT Center, 1976-1977.
Borerdamaged
Pods
pods harvested Yield
(%) (no) (kg/ha)
JG-62 (desi):
Sprayed 1.9 19096 1408
Not sprayed 8.2 20804 1324
L-550 (kabuli):
Sprayed 2.5 12019 972
Not sprayed 10.6 8153 626
more heavily attacked by H. armigera, particularly
during the flowering stage.
Pesticide Residue Analysis
D D T and endrin are the most commonly used
insecticides for H. armigera control on chickpeas,
but both of these chemicals have wellknown
disadvantages. We used endosulfan,
which has fewer disadvantages, but its relatively
high cost will discourage most farmers. Insecticide
use during the flowering and green-pod
stage introduces the possibility of toxic residues
in the harvested seed. Samples of seed from
endosulfan-treated plots were sent to the Tropical
Products Institute in England for toxicresidue
analysis. Endosulfan sulphate levels of
up to 0.34 mg/kg of seed were detected; such a
level may cause acceptance problems.
Screening for Susceptibility
It has been established that kabuli-type chickpeas
are generally more susceptible to H. armigera
attack than are the desi types and there is
some evidence to suggest consistent differences in
susceptibility within those types. This has encouraged
intensification of the work in developing
a screening program for "resistance" to H.
armigera.
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