Root traits for low input agroecosystems in Africa: lessons from three case studies

In Africa, agriculture is largely based on low-input and small-holder farming systems that use little inorganic fertilizers and have limited access to irrigation and mechanization. Improving agricultural practices and developing new cultivars adapted to these low-input environments, where production already suffers from climate change, is a major priority for ensuring food security in the future. Root traits improving water and nutrient uptake could represent a solution toward achieving these goals. In this review, we illustrate how breeding for specific root traits could improve crop adaptation and resilience in Africa using three case studies covering very contrasted low-input agroecosystems. First, we review how targeted changes in root system architecture allowed a dramatic increase in common bean yield in low input agroecosystems of South East Africa. We next discuss how root traits could be targeted to improve the productivity and resilience of dryland cereals in the face of climate change and soil degradation. Finally, we evaluate how root traits could be mobilized to develop water-saving rice agroecosystems for West Africa. We conclude with a discussion on how to prioritize target root traits, how they could be validated and made available to breeders and farmers through participatory approaches.