A field experiment conducted in 2013 and 2014 at the Agriculture Experimental Station of King
Abdulaziz University to study the effects of water deficit on growth, yield and irrigation water use
efficiency (IWUE) of three cowpea cultivars. The deficit irrigation treatments were applied at vegetative
(T1), flowering and bud setting (T2), bud filling (T3), vegetative and bud filling (T4) and flowering and
bud filling (T5) stages. The plants of cowpea provided with the full water requirements were used as
control treatment (T0). The experiments were laid out in split plot design using 3 replicates. The cultivar
‘Balady’ revealed significant increase in all assessed growth, yield component and yield parameters
and irrigation water use efficiency (IWUE) in both seasons except no. of seeds/pods in 2013. Applying
water deficit at vegetative growth stage significantly increased no. of branches/plant, no. of pods/plant,
no. of seeds/pod, weight of seeds/plant (g), weight of 100 seeds(g), total yield of dry seeds (kg/ha) and
IWUE (kg mm-1ha-1). Growing the plants under water deficit at the stage of flowering and pod filling (T5)
caused significant reduction in all measured growth, yield component and yield parameters as well as
irrigation water use efficiency (IWUE). Enhanced growth, yield and irrigation water use efficiency were
observed for plants of the cultivar ‘Balady’ under water deficit stresses at vegetative stage (T1). Least
performance was observed for plants of the cultivars ‘Carem7’ and ‘TVu9443’ under water deficit
stresses at vegetative and flowering stage (T4) and flowering and pod filling stages (T5). The cowpea
cultivar ‘Balady’ can be presented for cultivation under water deficit stresses particularly at vegetative
stage.