Response of two cowpea varieties to Sokoto rock phosphate in north-western Nigeria

Abstract

A pot experiment was conducted during the 2009 / 2010 dry season at the Teaching and Research Botanical Garden, Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto, to study the response of two cowpea varieties (Danzafi and IT89KD-288) to Sokoto rock phosphate (SRP). Four rates (0, 25, 50 and 75 kg ha^-1) of SRP were used, making eight treatment combinations which were laid out in a completely randomized design (CRD) repeated three times. The parameters measured included plant height, number of leaves, number of branches, shoot and root dry matter yields, plant tissue and residual nitrogen and phosphorus concentrations. The results showed significant (P < 0.01) differences among the rates of SRP and between the cowpea varieties with respect to plant height, number of leaves, number of branches, shoot and root dry matter yields and N and P concentrations in the plant tissues. Most of the parameters measured progressively increased significantly with increased SRP application and the 75 kg ha^-1 rate of application, led to the best performance of the cowpea varieties. Danzafi had higher shoot and root dry matter yield and plant tissue N and P concentrations, while ITA89KD-288 was taller, had higher number of leaves and shoot-root ratio. These are important indications of the optimal rate of application of SRP in the environment and an advantage of IT89KD - 288 over Danzafi. However, the experiment needs to be conducted under field conditions for validation purpose.