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The present study aimed at screening vegetable cowpea germplasm for
legume pod borer resistance and evaluation of partially resistant cultivars thus
identified for yield was carried out at the Department of Plant Breeding and
Genetics, College of Agriculture, Vellayani. Data for the investigation were
collected from two field experiments conducted during the period 1997-1999.
In the field screening programme for legume pod borer resistance, 51
diverse cultivars were evaluated on the basis of overall plant resistance index
(Ipr) computed using a combination of flower, pod and seed damage
measurements. The damage parameters employed in the computation of lpr
were number of larvae in 25 flowers, percentage pod infestation and seed
damage index (Jackai, 1982). Significant differences between cultivars were
observed for these damage parameters as well as the resistance index computed
based on them. Differences among cultivars in the severity of pod damage
assessed as number of entry / exit holes on pod samples were also significant.
The cultivar suffering least flower damage was Vs 27. The cultivars Vs
2 and 28 recorded the lowest percentage pod infestation as well as pod damage
severity. Cultivar with the lowest seed damage was Vs 13. Lower Ipr values
indicate higher levels of plant resistance. Consequently Vs 27 with the lowest
Ipr value was identified as the most resistant among the 51 cultivars. Other
cultivars on par with Vs 27 were Vs 2, Vs 7, Vs 8, Vs 10, Vs 19, Vs 28, ys 31
andVs35.

Correlation analysis of different damage parameters did not suggest any
relationship between flower and seed damages. Percentage pod infestation and
pod damage severity showed highly significant positive correlation between
. them but were uncorrelated with larval count in flowers. Seed damage was
found to be positively correlated with pod damage.
Despite differences in total leaf chlorophyll content among the cultivars,
the correlation between total leaf chlorophyll content and plant resistance
index was non-significant indicating the absence of any relationship between
them. Similarly peduncle length did not show any relationship with Ipr as well
as the different damage parameters. However, pod width was found to be
positively correlated with Ipr, pod damage severity and percentage pod
infestation. Non-glandular trichome density on pods recorded significant
negative correlation with Ipr and pod damage indicating that plant resistance
increases with increase in non-glandular trichome density on pods.
Fifteen top ranking cultivars with respect to legume pod borer
resistance were chosen and evaluated for yield and its components in a field
experiment in RBD with three replications.
Analysis of variances revealed significant difference among the varieties
for eleven out of the fourteen characters studied. The cultivar Vs 14 was the
top yielder of vegetable pods with Vs 24 on par with it. Highest pod length
was recorded by Vs 28 and highest pod weight by Vs 2. High heritability and
genetic advance were recorded for number of pods per plant, yield of vegetable
pods per plant and pod weight.

Number of pods per plant had high direct effect on vegetable pod yield.
Its correlation with yield was significant and positive. This suggested that
number of pods per plant is a character important in selection programmes for
yield in vegetable cowpea.
The cultivars Vs 14 and Vs 24 which were high yielders among the
partially resistant accessions were identified as varieties suitable for cultivation
in legume pod borer endemic areas.