Physiological Traits Affecting the Acquisition and Utilization of Phosphorous by Cowpea (Vigna unguiculata L. Walp.) Over Plant Development.

Besides nitrogen (N), phosphorous (P) is the most important inorganic nutrient for plant growth. However P is not a renewable nutrient like N, and the global availability of P for agriculture is depleting. Therefore crops must be developed to grow well in low P conditions. Cowpea (Vigna unguiculata L. Walp.) is a crop that would readily benefit if bred for low P conditions since its production in West Africa already is severely limited by low P in soils and high P costs. During cowpea seedling development, both cotyledon phosphorous (P) and extracted soil P are utilized. The present analysis will investigate the role of cotyledon P in cowpea seedling development in low-P and normal soils. The effect of clipping or removing cotyledons at various stages of seedling development on P mobilization and seedling growth will be determined. Further into cowpea development, phosphorous acquisition is often linked to secondary traits such as root surface area and root acid exudation. Therefore, the development of cowpea roots and their acid exudation will also be investigated in high- and low-P soils. The results of these experiments will lay the foundation for future cowpea phosphorous uptake experiments and genetic studies.