Tolerance to water deficit of cowpea genotypes

The objective of this study was to evaluate physiological and productive characteristics of cowpea under water deficit and total irrigation, under soil and climate conditions of Teresina, Piaui State, in 2008. The stomatal conductance, leaf water potential, leaf temperature and grain yield of twenty cowpea cultivars were evaluated. Two experiments were carried out in a randomized block design with 20 treatments and four replications, one under water deficit during the reproductive phase and another one under total irrigation. The water deficit was obtained applying half of the water depth required by cowpea. The water deficit reduced 72% of the stomatal conductance, 40% the leaf transpiration, 62% of the leaf water potential, 60% of the grain yield and increased 11.7% the leaf temperature. Under water deficit, 13 genotypes produced above average (466 kg ha(-1)), and BRS-Paraguacu, Pingo-de-ouro-1-2 and Pingo-de-ouro-2 presented the best grain yield with 712 kg ha(-1), 667 kg ha(-1) and 642 kg ha(-1), respectively. The average grain yield of the experiment under total irrigation was 150% higher.