Heterosis is the process of increase in vigour of F1hybrids over their parents. The term heterosis was first coined by George H. Shull 13.There are threetypes of heterosis, mid parent heterosis, better parent heterosis and usefulheterosis 14.
12Heterosisin grain legumes is due to dominance gene effects but sometimes due toepistasis effects 15. Heterosis inmungbean is significant for plant breeders to find out superior crosses andalso helpful to select desirable parents. Heterosis play vital role in F1 and F2generation because it provides a basis for determining genetic variability inmungbean 16. Geneticanalysis of hybrid vigour is important for the identification of hybridsshowing superiority over the parents and for better utilization of heterosis inmungbean breeding program. Heterosis for different yield and its attributingtraits were observed in the hybrids such as branches/plant ,pods/plant,100-seedweight and seed yield/plant 17.
Divergenthybrids of mungbean were studied to quantify the hybrid vigor for grain yieldand other quantitative traits. Genetic architecture of mungbean plantimproved through hybridization and develops some superior mungbean cultivarswith useful yield related traits such as total dry matter and harvest index18. Five mungbean lines were crossed with fourtesters to find out the nature of gene action, combining ability and heterosisfor yield and its attributing traits. Different traits such as days to 50%flowering, days to maturity, number of pods/plant, number of seeds/pod, dryweight/plant, seed yield/plant and harvest index has significance heterosisobserved19.Heterosis studies on mungbean were conducted betweentwo parents exotic and five native under controlled conditions. Midand better parent heterosis was recoreded in which data of plant height, pods/plant, pods length, seed/pod, 100 seedweight, biological yield/plant, harvested index .
Maximum heterotic effects wasobserved for pods/plant, grain yield/plant and harvest index in that crosses(NCM 87 x MI 5, NM13-1 x NCM 7, NM13-1 x T-77)20.Heterotic effects were studied overmid-parent and better parent in 8 parental diallel involving 3 local and 5exotic mungbean genotypes. Hybrids along with their parents were screened outfor different traits. Heterosis was observed in the different traits likenumber of pods/plant, grain yield/plant, and plant height. Strong heterosiswere observed for grain yield/plant and number of pods/plant in four F1hybrids (NM 51 x VC 3902, NM 20-21 x VC 1163, VC 3301 x VC 1163 and NM51 x VC 3902) 21.Five mungbeanvarieties (CM1 to CM5) from china, two from Thailand (KPS1 and KPS2P) and onefrom Korea (K7) were crossed to generate 34 F1 crosses.
Mid-parentheterosis and heterobeltosis was calculated for better agronomic traits.Maximum heterosis was observed in different yield and yield attributing traits22. Twenty eighthybrids of mungbean were established through 8 × 8 diallel excluding reciprocalcrosses. Significance of heterosis over better parent and standard check werecalculated. Maximum heterosis 80.76% over standard check and 72.39% over betterparent were observed for grain yield/plant 23.
