The objective of this study was to evaluate green grain yield, production components and water use efficiency for cowpea-bean under different water regimes. The experiment was carried out at Embrapa Meio-Norte, in Teresina, PI, Brazil, from September to November 2009. Five irrigation blades, based on reference evapotranspiration fractions (25, 50, 75, 100, and 125% of ETo), and the evaluated cowpea-ben cultivars were BRS Guariba and BRS Paraguaçu.Irrigation was performed by conventional fixed sprinkling system. The experimental designwas a randomized complete blockwith four replicates, in a split-plot arrangement (cultivars). Maximum green grain yields achieved 2,937.3 kg ha-1 for BRS Guariba and 2,492.9 kg ha-1 for BRS Paraguaçu; these productivities were obtained under 354 mm and 423 mm irrigation blade, respectively. The irrigation blades of 275 mm and 231 mm for BRS Guariba and BRS Paraguaçu cultivars, respectively, accomplished the most efficiency in water use for green grain yield. BRS Guariba shows a better performance compared with BRS Paraguaçu.
Vigna unguiculata; green bean; water blades
