A case study on the efficacy of root phenotypic selection for edaphic stress tolerance in low-input agriculture: Common bean breeding in Mozambique

Increasing common bean production, through the development and release of new phosphorus (P) efficient cultivars with improved root phenotypes in Mozambique was made possible by integrated physiology, agroecology, and social science research into a breeding pipeline. Social science research on small-holder farmers identified increased production in low fertility soils and ability to improve soil as primary constraints. Identification of root phenes improving P capture by physiological research enabled breeding to select for specific phene states rather than coarse yield-based metrics. This selection process targeted root phenes such as basal root whorl number (BRWN), basal root growth angle (BRGA) and long, dense root hairs. Agroecological research identified positive impacts of P efficient bean lines for enhanced utilization of rock phosphate, reduced soil erosion, greater biological nitrogen fixation, and acceptable competition with maize in polyculture. Socioeconomic research evaluated factors affecting adoption, dissemination and marketing and assessed the impacts of adoption of the new varieties on food security, farm income, women, children and men in specific rural populations. This case study illustrates how trait-based breeding programs, and specifically root ideotype breeding, can successfully utilize a multidisciplinary approach to release new varieties likely to be accepted by farmers and have broad impact on food security, small-holder farmer income and soil health.