Impact of Irrigation at Different Growing Stages on Yield, Crop Water Productivity, and Profitability of Cowpea ( Vigna unguiculata L.) in Bangladesh

Abstract

Usually, farmers apply irrigation once in cowpea production or cultivate in rainfed conditions. Randomized complete block design (RCBD) with three replications and five irrigation treatments were considered to explore the crucial crop stages for irrigation with respect to judicious water use and more economic return in cowpea production. There were irrigations at three weeks interval (T₂), irrigation at flowering stage (T₃), irrigation at pod formation stage (T₄), irrigation at flowering plus pod formation stages (T₅), and rainfed condition was regarded as control (T₁). The highest yield (2.26 ton Kg-¹) occurred in the most frequent irrigation events (T₂) which were about two times of rainfed condition yield (T₁). Irrigation at pod formation (T₄) was more responsive to yield, crop water productivity, benefit-cost ratio than irrigation at the flowering stage (T₃). Therefore, when there is a scope of one irrigation event, irrigation at pod formation should be applied. However, cowpea is a drought-tolerant crop since the yield response factor (K_y) of cowpea was 0.98 at a 1% level of significance which was less than the unity.