EPISTASIS FOR VEGETATIVE AND REPRODUCTIVE TRAITS IN PEANUT

Most genetic models assume absence of epistasis while estimating compo nents of genetic variation. However, epistasis when present introduces bias. These biased estimates affect the progress in a breeding progra m since they influence the choice of breeding methodology. The objecti ves of this study were to determine the significance of epistasis in t he inheritance of pod yield and related traits in 15 peanut (Arachis h ypogaea L.) cultigens, and to estimate the additive and dominance vari ances for the traits not influenced by epistasis, Two cultigens and th eir F-1 hybrid were each crossed to 15 cultigens from 13 countries, re presenting three botanical groups. The experiment was conducted in the 1992-1993 post-rainy and 1993 rainy environments at the ICRISAT Asia Center, Patancheru, India, The deviations were analyzed to detect epis tasis of 11 traits. Epistasis affected the expression of eight traits in both environments. Environments interacted more strongly with epist atic gene actions than with additive or dominance gene actions. Expres sion of epistasis was influenced by genotypes and environments, indica ting the need for more genotypes and environments for effective detect ion of epistasis. Evidence for additive genetic variance and lower lev els of partial dominance for canopy breadth and additive and dominance variances and complete dominance for shelling outturn was obtained in the post-rainy environment.