Prediction of tomato yield and water productivity under deficit irrigation scenarios using AquaCrop model in Afaka, Kaduna, Nigeria

Improving water productivity through deficit irrigation has become a major goal for sustainable agriculture amidst global decline in water availability. The study evaluated the yield, crop water use and water productivities of field-grown drip-irrigated tomato in response to regulated deficit irrigation, and subsequent simulation under different deficit and irrigation method scenarios, using AquaCrop model, in Afaka, Nigeria. The field experiment, laid in randomized complete block design, comprised three deficit irrigation levels (80, 60 and 40% of reference evapotranspiration, ETo) imposed at the vegetative, flowering and maturity growth stages, with 100% ETo at the three crop growth stages as the control. The highest fresh fruit yield (19.0 t/ha) was obtained irrigating with 100% ETo value at all growth stages but the highest water productivity of fresh fruit (4.94 kg/m3 ) was obtained irrigating with 60% ETo at maturity stage, then full irrigation at vegetative and flowering stages. On fruit dry yield basis, the highest simulated crop water productivity (0.46 kg/m3 ) for the deficit scenarios was obtained irrigating with 80% ETo at all the three growth stages, having the highest fruit dry yield (1.67 t/ha) and the lowest seasonal water applied (447 mm). Under the scenarios of irrigation methods (drip, basin and furrow), the fruit dry yield was similar in each treatment, but water productivity was highest (0.53 kg/m3 ) under drip irrigation system. Irrigating with 80% ETo at all the entire crop growth cycle of UC 82B tomato is recommended for the highest crop water productivity.