Influence of growth-stage-based deficit irrigation on tomato yield and water productivity in Kaduna, Nigeria

Improving water productivity (WP) through deficit irrigation is a major goal for sustainable agriculture under water scarcity conditions as observed in the semi-arid parts of Nigeria. The yield and crop water use responses of drip-irrigated tomato to deficit irrigation in Kaduna, Nigeria was evaluated during the dry seasons of 2017-2019. The treatments comprised three irrigation levels: 80, 60, and 40% of reference evapotranspiration (ETo) and three crop growth stages: vegetative, flowering, and maturity. In randomized complete block design, each irrigation level was imposed at a particular crop growth stage, in successions, while irrigating fully (with 100% ETo) at the other two growth stages. Full irrigation at the three crop growth stages was the control. The full irrigation gave the highest fruit yields of 19.0 t ha-1. However, the crop water productivity (CWP) was highest (4.91 kg m-3) when irrigated with 60% ETo at maturity, and full irrigation at vegetative and flowering stages, implying that 4.91 kg of tomatoes were produced for every cubic meter (m³) of water used. This is the recommended deficit strategy under water-limiting condition, subject to economic evaluations. The CWP value would be a benchmark for comparing WP across different tomato cultivars, irrigation systems, or farming practices.