NODULATION OF COWPEA

Abstract 

Cowpea (Vigna unguiculata [L]Walp) can obtain nitrogen from the atmosphere by the process of biological nitrogen fixation when associated with specific and effective rhizobia. The purpose of this study was to evaluate the effect of different rates of phosphate fertilizer on nodulation and dry matter yield of cowpea. A Randomized Complete Block Design with four treatments and three replications was used. The trial was conducted on the field. The treatments consisted of different rates of phosphates (0, 6.6, 13.2, and 26.4 kg P ha-1) that were applied to cowpea. Nodulation (nodule number and biomass), shoot biomass, root biomass and P concentration were determined. No significant difference (P>0.05) were obtained with P levels, although, 6.6 kg P ha-1 consistently gave higher values for the parameters measured in the Cowpea trials. Increasing phosphorus levels decreased nodulation and dry matter yield. This may be attributed to the high level of native P in the soil.

Keywords: Cowpea, nodulation, phosphate fertilizer, dry matter yield