Genotype x environment interaction in relation to combining ability in Indian mustard

Combining ability effects and variances were estimated sperately and over four environments (two dates of sowing in two years) from a half-diallel cross involving nine parents. Although both gca and sca variances were important, nonadditive variance was of greater importance than additive variance controlling number of siliquae on the main branch, total number of siliquae/plant, and seed yield/plant. Difference among the environments was significant for all the characters. Both gea x environment and sca x environment interaction variances were significant for all the characters studied, while further partitioning revealed higher magnitude of nonadditive x environment interaction than additive x environment interaction for all the traits. The variety Sita exhibited good general combining ability for number of siliquae on the secondary branches and total numberof siliquae/plantin at least two environments and over environments. Top ranking crosses selected on the basis of significant desirable sca effect involved high, medium and low general combiners.