MOLECULAR AND MORPHOLOGICAL DIVERSITY STUDIES FOR YIELD AND YIELD ATTRIBUTING CHARACTERS IN COWPEA [Vigna unguiculata (L.) Walp.]
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Date
2008-08-10
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University of Agricultural Sciences GKVK, Bangalore
Abstract
An investigation was undertaken to estimate the nature and extent of the genetic
variability, divergence among the 169 cowpea genotypes. Association of various
characters with yield and its attributing characters were also studied. Diversity at
molecular level was estimated using SSR markers and the molecular diversity was
compared with morphological diversity. The analysis of variance revealed significant
differences for all the ten characters including yield. The estimates of PCV and GCV
were high for all the characters except days to physiological maturity and plant height.
Positive and significant correlations of seed yield with plant height, number of branches,
clusters, pods per plant, number of seeds per pod and test weight was observed. Rath
analysis indicated that the traits number of pods per plant and test weight had high direct
effects on seed yield. Genetic divergence study using Mahalanobis D2 statistic grouped
169 genotypes into eight clusters. Maximum genotypes were grouped in the cluster VI
(5 I genotypes). Maximum contribution towards total divergence was by Seed yield per
plant. The genotypes were also screened against three major diseases viz. mosaic virus,
rust and leaf spot under natural conditions. Thirty lines were found resistant to all the
three diseases in the field condition. The genotypes TC99-1, EC170584-1-1, NBC43,
^ P58. V240 and IC202711(58) were found superior to checks and were showing high
yield as well as multiple disease resistance under natural field condition. Fifty
representative genotypes were selected for molecular characterization. The results
revealed 45 to 100 per cent similarity between the lines at molecular level. Clustering of
the morphological data was carried out using correlation coefficient. The genotypes
exhibited 88 to 100 p e rc e n t similarity at morphological level. The study revealed that
diversity at molecular level was very high compared to diversity at morphological level,
suggesting higher resolution for diversity from molecular data than morphological data
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