Combining Ability of Commercial White Pea Bean (Phaseolus Vulgaris L.) Varieties in South Western Ethiopia

Abstract

The diallel mating design, that produces all possible single crosses among a set of inbred lines has been widely utilized to provide information on the potential of parents involved in hybrid combinations as well as inferences on genetic control of the traits under investigation. It is an important tool, which aids in statistically separating progeny performance in to components relating to general combining ability (GCA), and specific combining ability (SCA). 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. 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. 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. 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.

Keywords: White pea bean, SCA, GCA, reciprocal effects, maternal effects, Non-maternal effects