Targeted Analysis of Dry Bean Growth Habit: Interrelationship among Architectural, Phenological, and Yield Components

Abstract

An ideotype breeding strategy to improve an economically important trait is achievable if subcomponent phenotypes most associated with the trait are targeted for selection. The success of this strategy in modern breeding history can be highlighted in dry bean (Phaseolus vulgaris L.), where an enhancement in dry bean production was facilitated in the last 25 yr by replacing Type III prostrate growth habit with Type II upright growth habit. This growth habit leads to disease avoidance and enables cost‐effective management practices. To better understand the ideotype breeding trajectory in dry bean, and guarantee further improvements, we characterized 16 traits at three locations using a panel consisting of 122 genotypes with different growth habits. Among the growth habit types, significant differences were detected for seven architectural traits, three seed yield (SY) traits, and one phenological trait. Genetic variance was greater in the Type II genotypes than the Type III genotypes for five of the significant traits, including canopy height (CNH) and SY. Furthermore, in Type II genotypes, moderate narrow‐sense heritability was detected for CNH, lodging (LDG), plant length (PL), and stem diameter (STD), suggesting positive gain can be made for growth habit from crosses between Type II genotypes. A network analysis of Type II genotypes revealed these four traits are highly correlated, and suggests possible genetic relatedness among the traits. Breeders often use CNH as a selection criterion, and the positive correlation between this trait and STD suggests a possible anatomical mechanism responsible for the more upright plant types.