Heterosis and inbreeding depression for pod yield and its related traits in Spanish bunch groundnut (Arachis hypogaea L.)

A diallel analysis excluding reciprocals using eight genotypes was carried out to study the extent of heterosis and inbreeding depression for pod yield and yield attributing characters in bunch groundnut. The study revealed that heterosis over mid parent and better parent and inbreeding depression was observed for all the traits studied. The cross TG 19A x Chico exhibited significant and positive relative heterosis (52.87%) and heterobeltiosis (50.09%) alongwith maximum mean performance (13.49 g). It also expressed significant and high inbreeding depression (32.53%). Other crosses viz., GG-7 x Chico, SB-XI x JL-24 and FeESG-10 x JL-24 also expressed high heterobeltiosis alongwith high inbreeding depression for 100-kernel weight, shelling outturn and kernel yield per plant. Negative estimates of heterotic effects for some of the traits may be attributed to inter-allelic interactions. In general, crosses showing high heterosis also exhibited high inbreeding depression for pod yield and its attributing characters. Nonadditive gene action with over dominance as indicated by close relationship between heterotic and inbreeding depression was observed for pod yield and its related traits. Based on these results, selection of segregants from the cross TG-19A x Chico is suggested for further continuation to achieve improvement in the pod yield and ultimately kernel yield. The method suggested is to make individual selection to intermate the selection then further select in the segregating generations of the cross.