Effect of Growth Stage-based Water Stress on Yield and Water Use Efficiency of Tomatoes (Solanum lycopersicon L.) in Semi-arid Regions of Tigray, Ethiopia

Water availability is a major concern in regions with limited water resources. Implementation of best irrigation water management methods can maximize crop yields and irrigation water use efficiency. An experiment was conducted in Laelay Koraro district, Tigray, Ethiopia for two consecutive years (2018 and 2019 off seasons) to investigate the effect of growth stage-based deficit irrigation on tomato yield, yield characteristics and water usage efficiency. The experiment used a randomized complete block design (RCBD) with three replications. The treatments were three irrigation levels (100%, 50%, and 25% of crop irrigation requirement) and four FAO-defined tomato growth stages (initial, developmental, mid, and late seasons). Data on agronomic parameters and irrigation water were collected and analyzed statistically. The results revealed that reducing irrigation amount by up to 75% during the development growth stage significantly decreased marketable yield by up to 66.5%. However, the highest water use efficiency (9.2kgm-3) was achieved by reducing irrigation amount by 75% at the end-growth stage of tomato. Treatments with the lowest water use efficiency (3.5kgm-3) were those receiving 75% less irrigation amount than the full requirement during the development growth stage. Irrigation deficit up to 75% of the full requirement during tomato development stages greatly affect marketable yield and water use efficiency. Therefore, the tomato crop is highly susceptible to water stress when receiving more than a 50% reduction in full irrigation requirement during its developmental growth stage.