Research Article Genetic structure of root distribution in genotype crosses of Mesoamerican common bean

Abstract

Knowledge of the genetic structure of a trait shapes the entire strategy of a breeding program. In this study, the purpose was to determine the additive and non-additive effects that affect the genetic control of common bean roots. A field experiment, with 75 treatments in a partially balanced incomplete block design, was carried out in the 2018/19 growing season. The treatments consisted of backcross progenies (L1 P1 x F2, L2 P2 x F2 and L3 F1 x F2) resulting from a Triple Test Cross mating design, with the Mesoamerican parents P1-BAF50 (accession of the active germplasm bank) and P2-IPR Uirapuru (commercial cultivar). The trait root distribution was assessed based on the soil excavation method, in situ. To this end, trenches were opened under each plant (two plants per replication, in each treatment) and a grid was inserted in the open profile. Pictures were taken of the grid in the trench, based on which the root distribution (percentage) could be quantitatively assessed. To compare root and shoot biomass, the numbers of pods and grains were counted at harvest. The treatment factor was partitioned into genetic effects (additive, dominant and epistatic) by the establishment of predictive functions. The additive genetic effect was the most