A field experiment was conducted at Teaching and Research farm of Landmark University to investigate the influence of three population densities (88,000, 44,000, and 29,000 plants/ha) on the growth and yield of five cowpea varieties (IT97K-461, IT97K-568-18, IT98K-131-2, IT99K-1060 and IT99K-`245). Plant growth parameters such as germination count, plant height, and number of trifoliate leaves per plant, number of branches per plant, flower production dynamics and dry matter determination were measured during growth, and yield components such as harvest index, shelling percentage, number of seeds per pod, see weight pods per plant and grain yield were measured at harvest. Results showed that there were no constant trends in growth parameters response to population density. Plant height and flower production decreased with increased population density, while number of leaves per plant and dry matter increased with increasing population density. There was no appreciable effect of population density on branching. All these parameters were significantly affected with variety, while there was no significant interaction effect. Most yield components decreased with increasing population density while grain yield however, slightly increased with increasing population density. All yield parameter and grain yield significantly varied with variety, while there were no appreciable interaction effect. In concussion, a population density of 88,000 plants /ha gives the highest growth and grain yield. It can therefore be recommended. Also variety, IT97-568-18 gives the higher growth and grain yield than other varieties.
Keywords: Genetic effects, growth, Vignaunguiculata, population density.