A two-year field study was conducted to characterize the effect of water deficit imposed during one or more growth stages on the production of cowpeas (Vigna unguiculata (L.) Walp). Plant growth, plant-water potential, soil-water status, and weather parameters were measured. Five different models for potential evapotranspiration were compared with measured evapotranspiration from a well-watered crop during the full cover stage. Only those methods which included a vapor-deficit correction for advection effectively described potential evapotranspiration in southern California.
