Parental effects and provisioning under drought and low phosphorus stress in common bean

Low soil fertility and drought are primary constraints for crop production and food security in many developing nations. Since smallholder farmers often collect seed for the next year's crop from plants grown with abiotic stress, it is important to understand how progeny from a stressed parental environment perform when they are grown under similar stresses. This study investigates the impact of a low phosphorus (P) or drought parental environment on progeny seed and root traits in common bean (Phaseolus vulgaris), with the intention of distinguishing impacts of reduced parental provisioning from adaptive responses. Greenhouse, field, and seedling experiments were used to evaluate seed, seedling, and mature root phenotypes in progeny from stressed and nonstressed parental conditions. In addition, progeny from different positions within the pod and pod developmental times were evaluated since they are expected to vary in parental provisioning. Seeds from the peduncular position in the pod had less individual seed weight, fewer basal roots, reduced root dry weight, and smaller taproot diameter than those from the stylar position. Progeny of some genotypes from drought-stressed parents had smaller individual seed weight, fewer basal roots, less total seedling dry weight, shorter seedling basal roots, and smaller basal root diameters. Progeny of some genotypes from a low P parental environment had smaller individual seed P concentration, fewer shoot-borne roots, and greater basal root whorl number. Progeny from drought-stressed parents, progeny from a low P parental environment, and seeds from the peduncular position had root phenotypes that were likely to be related to less parental provisioning. Possible adaptive parental effects were found in both parental drought and parental low P studies. Adequate seed provision under stress merits consideration as a selection target in crop breeding for stressful environments.