Performance of cowpea (Vigna unguiculata (L.) Walp) under irrigation as influenced by weed management methods and intra row spacing

Abstract

The study was conducted in the dry season of 2014/2015 at two locations: the experimental Farms of the Institute for Agricultural Research, Ahmadu Bello University Samaru, Zaria and Kadawa Kano, located in the Northern Guinea and Sudan Savanna Ecological Zones of Nigeria, to assess the effects of weed management methods and intra row spacing on performance of cowpea. The experiment was laid out in a split plot design with three replications. Treatments were five weed control methods involving the use of Pendimethalin at 1.0, 1.5 and 2.0 kg a.i. ha-1, two hoe weeding at 3 and 6 weeks after sowing (WAS) and a weedy check and four intra row spacing (20, 25, 30 and 35 cm). The herbicide treatments were assigned to the main plots while intra row spacings were assigned to the subplots.  Results indicated that weed coverage score, weed density and weed dry weight were significantly decreased by the weed control methods compared to weedy check treatments. The application of Pendimethalin at the rate of 2.0 kg a.i ha-1 and two hoe weeding at 3 and 6 WAS resulted to significantly higher values for plant height, canopy spread and crop growth rate. Yield parameters including number pods per plant, seed weight and grain yield were also significantly increased in the herbicide treated plots and two hoe weeding compared to weedy check. In conclusion, the results obtained from this study indicated that two hoe weeding at 3 and 6 WAS and 20 cm intra row spacing effectively controlled weeds and produced the highest grain yield (kg ha-1) in Samaru, Zaria and Kadawa, Kano.