Influence of defoliation on seed yield in cowpea [Vigna unguiculata (L.) Walp.] in a sub-tropical environment

Abstract

Abstract Four field experiments were carried out to determine the effect of defoliation on growth and seed yield of cowpea. Defoliation during the vegetative and/or the reproductive phase reduced seed yield. The magnitude of yield reduction was dependent on stage of crop development and degree of defoliation. The removal of one-third and two-thirds of the leaves during the vegetative and reproductive phases (25–49 days after planting) reduced seed yield. However, one-third defoliation during late-pod filling did not affect seed yield. Complete defoliation 1 to 3 weeks after anthesis was very detrimental to seed yield because it lowered the number of pods and seeds per pod. The results suggest that cowpea grown under a subtropical environment cannot compensate for foliage loss during the vegetative or early reproductive phases.