WATER DEMAND AND TECHNICAL-ECONOMIC VIABILITY OF COWPEA GROWN IN DIFFERENT PRODUCTION SCENARIOS

Water demand and agronomic and economic efficiency of cowpea are strongly related to agricultural practices and climatic conditions. This study aimed to determine in which cropping season cowpea has the highest water demand and maximum agronomic and economic efficiency as a function of water stress under the edaphoclimatic conditions of the semi-arid region of northeastern Brazil. Cowpea was cultivated in two cropping seasons (rainy and dry) and subjected to five forms of water stress (without water stress, water suspension for 5, 10 and 15 days and rainfed cultivation) and four replicates, started in the flowering and grain filling stages, under no-tillage system. Agronomic (yield, biomass, harvest index and water use efficiency) and economic (gross revenue, net revenue, rate of return and profit margin) parameters were evaluated. The water demand of cowpea in the dry season was 20.2% higher than in the rainy season; consequently, the Kc values obtained were also higher in this period. The climatic conditions that occurred during the cropping seasons and water stress negatively influenced the agronomic performance and financial profitability of cowpea, being more evident in the rainfed cultivation. For the edaphoclimatic conditions of the study, cowpea can be grown without significant losses of yield and profitability in both cropping seasons, provided that the water stress does not last more than 10 days during its reproductive stage.