GENETIC ARCHITECTURE OF YIELD, ITS COMPONENTS AND QULITY TRAITS IN INDIAN BEAN (Lablab purpureus var. typicus)

Indian bean is a leguminous vegetable crop. Due to wide variability, it holds potential for further improvement. The present investigation on Indian bean comprised of a 9 parents and their 36 half-diallel crosses. The check variety Valor Virpur was used as one of parents. The experiment was laid out in a randomized block design with 3 replications at Main Vegetable Research Station, Gujarat Agricultural University, Anand, during rabi 2003-2004. Combining ability, components of genetic variance, graphical analysis and heterosis were studied for 13 characters, viz. days to flowering, plant height (cm), primary branches per plant, pods per plant, pod length (cm), pod width (cm), pod weight (g), seeds per pod, 100 green seed weight (g), 100 dry seed weight (g), green pod yield per plant (g), moisture content (%) and protein content (%). The analysis of variance indicated significant differences among genotypes for all the characters. The mean sum of squares for parents (except primary branches per plant), hybrids and parents vs. hybrids (except pods per plant, pod width, seeds per pod) were also observed significant for all the traits. The gca and sca variances were significant for all the traits except sca mean squares for pods per plant and green pod yield per plant. This indicated that both additive and non-additive gene actions played important role for the inheritance of these traits. However, potence ratio indicated preponderance of additive gene action for days to flowering, plant height, pods per plant, pod length, pod width, pod weight, seeds per pod and green pod yield per plant. Whereas, for rest of the traits non-additive gene action found predominant. The estimates of gca effects revealed that parents AIB(V)-1, AIB(V)-24 and AIB(V)-8-1 appeared to be good general combiners for green pod yield per plant and some of the other yield and quality attributes. A close relationship was found between per se performance and gca effects of parents. The estimates of sca effects indicated that cross combinations AIB(V)-1 x AIB(V)-4, AIB(V)-24 x Valor Dantiwada and AIB(V)-1 x JIB(V)-32 were significant for green pod yield and some of its related characters. There was some degree of correspondence between per se performance and sca effects of hybrids as well as sca effects and heterosis for most of the traits. Assumptions basic to diallel were fulfilled for days to flowering, pod length, pod width, seeds per pod and green pod yield per plant. The component and graphical analysis also revealed the importance of both additive and non-additive genetic variances for the inheritance of these traits. Degree of dominance indicated overdominance for seeds per pod and green pod yield per plant, while partial dominance for days to flowering, pod length and pod width. Positive and negative alleles were distributed asymmetrically for days to flowering, pod length, pod width, seeds per pod and green pod yield per plant. Higher frequency of dominant genes were found in the parents for days to flowering, pod length and seeds per pod, while higher frequency of recessive genes for pod width and green pod yield per plant. The heritability estimates were observed to be moderate for days to flowering and pod length and low for pod width, seeds per pod and green pod yield per plant. The findings have been discussed in the light of their implications in Indian bean breeding programme. Present findings indicated that breeding approaches like reciprocal recurrent selection and biparental mating are suggested for the improvement of these traits.