Published online by Cambridge University Press: 27 March 2009
Field experiments were conducted at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, for four seasons to evaluate the effect of harvest interval on yield, quality and viability of indeterminate cowpea (Vigna unguiculata (L.) Walp.) seeds. Decreasing harvest frequency from every week to every 4 weeks reduced seed yield, quality and viability. Rate of yield losses was highest at close spacing and intermediate at wide spacing during the first rainy season, and lowest at wide spacing with supplementary irrigation during second rainy season. Time of harvest study conducted with six cultivars indicated that these yield losses were attributable to reduced seed weight and increased pod losses after mature pods were exposed to weathering for more than 1 week. The reduction in seed quality and viability was associated with a high degree of fungal and bacterial infection in the seed. Varietal differences in resistance to weathering were noted among the cultivars tested. TVu 2616 P-O1D, that has thick, leathery pods and smooth, tan seed coat was the most resistant to weathering.