ABSTRACT
The study was conducted in the Hydraulic Irrigation Laboratory Experimental Area of the Federal University of Ceará in order to determine the cow pea bean crop yield factor (ky) under water deficit at different phenological stages. The experimental design consisted of entirely randomized blocks with eight treatments and four replicates. The treatments were established according to the time of the water deficit induction at the crop phenological stages and that corresponded to the occurence of the water deficit at one, two or three stages. The water deficit was obtained by applying half of the water depth used for the non-deficit treatment. The maximum and real cow pea crop evapotranspirations were determined by using the water balance method and the crop water deficit sensibility coefficients were calculated by using the equation ky=[1-(yr/ym)]/[1-(ETr/ETm)]. The grain filling stage was the one most sensitive to the water deficit when this was applied in just one stage, indicating low sensibility of the crop to the water stress.
Key words:
Vigna ungüiculata; water deficit; evapotranspiration