Abstract:
A 6 x 6 F2 diallel experiment (without reciprocal) on Lablab bean (Lablab
purpurezt L.) was conducted to study combining ability and inheritance in some
selected genotypes for pod yield and other related characters such as flowering, pod
setting, no. of inllorescences per plant, no. of flowers per inflorescence, no. of pods
per inflorescence, inflorescence length, pod length, pod width, 10-pod weight and
20-seed weight.
There were significant variations among the genotypes for all the characters
studied. Variances for general combining ability (gca) and specific combining
ability (sea) were significant for ten out of eleven characters including pod yield
per plant, suggesting the presence of both additive and non-additive components in
the genetic systems of these characters. For days to l' flowering and I St pod setting,
the genetic system was predominantly of non-additive gene action. The parental
genotype DS-52 was found to be the best general combiner for early flowering, pod
setting and 20-seed weight. The parent DSN-26 was the best general combiner for
inflorescences per plant, pod length, pod width, 10-pod weight and also for pod
yield per plant. For sea effect the cross DS-52 x DS-161 and DS-30 x DSN-26
were the best specific combiners for early flowering and early pod setting. For 10-
pod weight and pod yield per plant the cross DSN-26 x KBS-3 and DS-30 x KBS-2
were the best specific combiners.
Vr-Wr analysis relating to graphical presentation of major genetic features
were done for all the eleven characters. Complete dominance was observed for pod
yield per plant, partial dominance for no, of flowers per inflorescence, pod length,
10-pod weight, and 20-seed weight. While overdominance was recorded for days to
l flowering, days to 1M pod setting, no. of infloreseenees per plant, no. of pods per
inflorescence, inflorescence length and pod width.
Components of variation and various genetic parameters such as degree of
dominance, dominance ratio, narrow sense heritability etc. were estimated. Results
showed that positive and negative alleles were in unequal proportion among the
parents for all characters. The dominant alleles were in excess for all characters
except pod length, pod width and 20-seed weight. Dominant and recessive genes
were unequally distributed in the parents for all characters. High narrow sense
heritability was observed for pod yield per plant and 10-pod weight, whereas for
the others it was moderate to poor.
