Legume pod borer resistance and genetic divergence in domestic germplasm of yard-long bean (Vigna unguiculata ssp. sesquipedalis(L.) Verdc.)
Loading...
Files
Date
2000
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Plant Breeding and Genetics, College of Agriculture, Vellayani
Abstract
The present study aimed at the evaluation of variability in domestic
germplasm of yard-long bean for yield, and legume pod borer resistance
was carried out at the Department of Plant Breeding and Genetics, College
of Agriculture, Vellayani. Data for the investigation was collected from
two field experiments conducted during the period 1998-2000.
Fifty diverse genotypes of yard-long bean were evaluated for
yield and related characters in a field experiment in randomised block
design with three replications. Analysis of variance revealed significant
differences among the varieties for all the twelve characters studied.
High PCV and GCV were observed for yield of vegetable pods per plant,
number of pods per plant, number of pods per inflorescence, length of
main stem and pod weight. High heritability coupled with high genetic
advance were also observed for these characters.
Pod yield per plant showed high positive correlation with number
of pods per plant, number of pods per inflorescence, pod weight and
length of harvesting period. at genotypic level. Path analysis revealed
that number of pods per plant and pod weight were the primary yield
contributing characters owing to their high direct effect on pod yield.
2
So selection based on these characters will result in improvement of
yield in yard-long bean.
Based on Mahalanobis D2 statistic, the 50 cultivars were grouped
into four clusters. Cluster I formed the largest cluster with 28 varieties
while cluster IV had only a single cultivar. The genetic distance was maximum
. '
between clusters I and IV and minimum between clusters III and IV. Cluster
I had the highest intracluster distance. The single variety Vs 47 of cluster
IV was identified as the highest yielder of green pods. Hybridisation of this
variety with varieties having high pod number per plant or pod weight would
be beneficial. The cultivars Vs 45 and Vs 49 belonging to cluster III possessed
the highest pod weight and pod number per plant respectively. So hybridisation
programmes utilising these varieties as parents is worthy of consideration
for developing high yielding varieties in yard-long bean.
In the field screening programme for legume pod borer resistance
all the 50 yard-long bean cultivars were evaluated on the basis of overall
plant resistance index (Ipr} computed using a combination of flower, pod
and seed damage measurements viz., number of larvae in 25 flowers,
percentage pod infestation and seed damage index (computed based on
the number of damaged seeds in a sample of 25 pods) respectively.
Cultivars showed significant differences among them for these damage
. parameters as well as for resistance index computed based on them.
The cultivars suffering least flower damage were Vs 5 and Vs 33.
Lowest pod damage were recorded for the cultivars Vs 34, Vs 39 and
Vs 42. Seed damage index value was the lowest for cultivar Vs 2.
3
Vs 34 with the lowest Ipr value was identified as the most resistant
among the 50 yard-long bean varieties. The cultivars Vs 2, Vs 29, Vs 39
and Vs 42 were on par with Vs 34.
Correlation analysis of the different damage parameters did not
suggest any relationship between flower damage and pod damage or seed
damage. However pod damage showed high positive correlation with seed
damage.
Cluster analysis based on the different damage parameters enabled
to group varieties into seven clusters. Based on cluster means of the
various damage parameters, cluster IV and I were those suffering least
flower and pod damage respectively. So hybridisation programmes
utilising varieties from these two clusters could lead to the production
of varieties with higher level of legume pod borer resistance.
Studies on relationship between pod damage and two pod
characters viz., pod wall thickness and fibre content of pods indicated
that these pod characters did not influence infestation and damage by
legume pod borer.
Based on superior yield performance and high level of resistance
to legume pod borer, the cultivar Vs 42 is identified as a variety suitable
for cultivation in legume pad borer endemic areas. Further, breeding
programmes utilising the varieties with high yield and legume pod borer
resistance identified in this study could help in evolving better yielding
varieties with resistance to pod borer in yard-long bean.
Description
PG
Keywords
null
Citation
171736