Combining ability of commercial white pea bean (Phaseolus vulgaris L.) Varieties under jimma condition

Abstract

Combiningability study provides very useful genetic information about the ineheritance of quantitative traits that helps to determine the type of breeding procedure to be employed to improve the crop of interest. The objective of the study was to determine the type of gene actions involved in the inheritance of the most important quantitative traits in commercial white pea bean cultivars. Forty nine entries (7 parents and 42 F2 diallel crosses) were grown in a simple lattice design with two replications at Jimma Agricultural Research Center, South Western Ethiopia. The results revealed significant mean squares in all of the characters, except for days to 50 % flowering, days to maturity, number of nodes on the main axis, and internode length. There were significant mean squares due to general combining ability, specific combining ability, reciprocal effects, maternal effects, and non-maternal effects in almost all of the characters. The relative contribution of specific combining ability was higher than general combining ability for all of the studied traits, except for days to 50% flowering, pod length, and seed thickness.This indicating that the non-additive gene actions are influential in the expression of these traits which poses some difficulty as the non-additive gene actions are non-fixable. Thus, selfing should continue for more generation to fix the non-additive gene actions before undertaking selection. Significant general combining ability and specifi combining ability effects were found for leaf rust and angular leaf spot, respectively. This indicates that additive geneaction is important in the inheritance of rust and the segregating generation can be improved by selection. Starlight is good general combiner for 100-seed weight and grain yield. The other genotypes may also be good general combiner for other traits because they displayed positive and significant traits.