Response of Cowpea (Vigna unguiculata L. Walp.) to Water Stress and Phosphorus Fertilization

This study was conducted in the experimental college of agriculture and forestry, in Maputo-Mozambique, in order to evaluate the response of cowpea (Vigna unguiculata L. Walp.) to irrigation and phosphorus and test the hypothesis that high levels of phosphorus improves the tolerance of plants to water stress. We used a variety IT 18 of cowpea, short cycle and ended. The experiment was subdivided into building plots complete block design with five repetitions, the irrigation factor was fixed at the main plot with two levels (with irrigation and without irrigation) and phosphorus factor in sub-plots with 3 levels (0, 20 and 40 kg ha-1 of phosphorus). The fertilization strongly influenced the yield and the number of pods per plant in both irrigation conditions. The effect of fertilizing phosphorus was higher under irrigation. The interaction was significant only for grain yield and number of pods, which means that the effect of phosphorus in these two variables has not been the same for the two levels of irrigation, high levels of phosphate fertilizer (P2O5) have improved the tolerance of cowpea when not irrigated.