Diallel analysis to choose parents for black bean (Phaseolus vulgaris L.) breeding

In this study, conducted in two different seasons, we aimed to choose parents to obtain promising segregating populations for the extraction of black bean (Phaseolus vulgaris L.) lines that are superior in terms of disease resistance, plant architecture, and grain yield. Twelve parents were arranged in two groups to compose a partial diallel in a 5 x 7 scheme. Group 1 was composed of parents with black grains and erect plant architecture, while group 2 was composed of parents that had carioca grains and were resistant to the main fungal diseases that occur in the common bean. The following traits were evaluated: severity of angular leaf spot (ALS), plant architecture (PAG), and grain yield (YIELD). The data were analyzed according to a partial diallel model using parents and F₁ hybrids. In the genetic control of ALS and PAG, additive effects were predominant, while for YIELD, additive effects were predominant in one season and dominance effects were in another season, because it is a more complex trait than ALS and PAG. For YIELD, we observed an interaction between general combining ability and specific combining ability between seasons. The genes that control ALS, PAG, and YIELD were in eight of the 12 parents evaluated in the diallel. The cultivar 'BRS Estilo' is suitable to use as a parent in common bean breeding in terms of ALS, PAG and YIELD. Recurrent selection is the most recommended option for simultaneously breeding for PAG, YIELD, and resistance to angular leaf spot in bean culture.