ACTUAL CROP COEFFICIENTS AND YIELD RESPONSE FACTORS OF IRRIGATED TOMATO IN AFAKA, NORTHWEST NIGERIA

In the face of the prevailing challenges of limited water for irrigated agriculture, the knowledge of crop coefficients for use in irrigation, and the yield response to moisture stresses become pertinent for developing strategies to improve agricultural water productivity. Field experiments were conducted to evaluate the crop coefficients and yield response factors of UC 82B tomato subjected to soil moisture stresses on growth-stage basis. The irrigation treatments investigated were: a full irrigation (application of 100% ETo), and three soil moisture deficit levels (20%, 40%, 60% ETo) imposed at the vegetative, flowering and maturity growth stages, in successions. The mean crop coefficient (Kc) was highest (0.99) during the mid-season under full irrigation, and lowest (0.47) during the vegetative stage under 60% ETo soil moisture deficit, while the mean value across the entire crop growth stage was 0.88. The yield response factors (Ky) were 1.26 and 1.30 for the 2017/2018 and 2018/2019 seasons, respectively. The mean Ky of was 1.28 for the entire growth cycle, implying high sensitivity of the tomato cultivar to water deficits, and that yield reduction is proportionally larger when water used is reduced because of stress. Full irrigation at the maturity stage is recommended.