Field‐Based screening methodology to improve tolerance of common bean to low‐P soils

Abstract

Phosphorus (P) limits common bean (Phaseolus vulgaris L.) production throughout sub‐Saharan Africa, where P fertilizer is not affordable to the vast majority of smallholder farmers. Genetic differences in bean performance in low‐P soils suggest that low P tolerance could be improved. Earlier breeding efforts have not been successful, in part due to the challenges of selecting genotypes with improved performance in a heterogeneous soil environment. A field based screening method for low P tolerance has been developed, based on evaluating soil status and ameliorating edaphic compounding factors. The soil is classified as an Oxic Haplustalf and is representative of the unimodal, mid‐to‐high altitude bean growing regions of Southern Africa. The soil has very low zinc (Zn) and nitrogen (N) contents, which reduced growth markedly. After amelioration of these edaphic complications, P response could be quantified. A promising genotype CAL 143 was selected which consistently expressed, over two growing seasons, low P tolerance and high yield responsiveness to moderate fertilizer P application.