Effects of Variety and Planting Density on the Incidence of Common Viral Diseases of Cowpea ( Vigna unguiculatd) in a Southern Guinea Savannah Agro-ecology

摘要

Virus diseases are a limiting factor in cowpea production in all agro-ecological zones of Nigeria and yield reductions of between 80-100% have been reported. Some cowpea varieties show resistance to viruses, cultural practices such as varying plant population have been found useful in the control of these viral pathogens. Field experiments were conducted in the 2009 and 2010 cropping seasons to evaluate the effect of crop variety and varying planting density on the incidence of common viral diseasesof cowpea. Vigna unguiculata (L.) Walp in the Southern guinea savannah agro-ecology of Nigeria. This is to identify tolerant varieties and an optimum planting density that could lead to lower viral incidence and high crop yields. A split-plot fitted intoa randomised complete block experimental design with three replications was established with three cowpea cultivars (IT89KD-288, IAR-48 and Ife brown), in the main plots and three planting densities (25x75, 50x75 and 75x75 cm) in the sub-plots. The results of the study indicated that variety and planting density had significant effect on viral disease incidence. The lowest incidence was in variety IT89KD-288 (10.3%) while the highest was in variety IAR-48 (28.6%). The lowest mean incidence was also inplots under planting density of 25x75 cm. However, planting at a mid-level density of 50x75 cm with variety IT89KD-288 outperformed the other combinations for yields and is therefore, recommended.