GENETICS OF YIELD AND ITS ATTRIBUTES IN MUNG BEAN [Vigna radiata (L.) Wilczek]

Six generation i. e. P1, P2, F1, F2, BC1 and BC2 of nine crosses viz., Co-4 x K-851, Co-4 x Pusa bold-1, Co-4 x Pusa 9632, VRMGg-1 x K851, VRMGg-1 x Pusa bold-1, VRMGg-1 x Pusa 9632, GM-4 x K-851, GM4 x Pusa bold-1 and GM-4 x Pusa 9632 of mung bean (Vigna radiata (L.) Wilczek) were grown in two seasons viz., summer and kharif 2003 at college farm, N. M. College of Agriculture, Navsari in randomized block design replicated thrice, with a view to study the extent of heterosis, inbreeding depression, heritability, genetic advance and nature of gene action governing grain yield and its attributes. The analysis of variance revealed significant differences among various generations for majority of the characters in all the crosses indicating presence of appreciable amount of variability in the materials tested. Inadequacy of additive-dominance model was evident by the significance of scaling tests A, B, C and D as given by Mather (1949) indicating presence of non-allelic gene action in most of the crosses for various traits studied. Crosses VRMGg-1 x Pusa 9632, GM-4 x K-851 and VRMGg-1 x K-851 recorded significant positive heterosis over better parent for grain yield per plant and its related components. The per se performance of these crosses was also higher for the respective traits in summer season. Similarly, during kharif crosses Co-4 x Pusa bold-1, Co-4 x Pusa 9632 and VRMGg-1 x K-851 depicted high per se performance for grain yield and majority of its components with significant high positive heterobeltiosis. Crosses showing high heterotic effects for grain yield and its components also manifested significant inbreeding depression which indicated involvement of dominance gene effects in the expression of the various traits. The results revealed that both additive and dominance gene effects were significant for majority of the traits in all the nine crosses studied, however the magnitude of dominance gene effects was much higher than the additive effects in all the crosses for majority of the traits which indicated pre-dominant role of dominance gene effects in the inheritance of grain yield and its related traits. Among epistasis gene effects dominance x dominance played important role in the expression of grain yield and its related traits like pods per plant, pod length, 100-seed weight and harvest index in majority of the crosses while additive x dominance showed major contribution in the expression of branches per plant. For clusters per plant and days to 50 per cent flowering, additive x additive played predominant role in majority of crosses. Magnitude of non-fixable component was high for grain yield and some of its components. Diallel selective mating or biparental mating in early segregating generations might prove to be effective approach in further enhancing the grain yield. In some of the crosses fixable components were significant, positive and of considerable magnitude for yield components like clusters per plant, pods per plant, pods per cluster and 100-seed weight. Directional selection would be beneficial in isolating more efficient segregants in these crosses for important yield attributes which ultimately helps in further elevating the yield potential. C E R T I F I C A T E