Determination of Optimal Irrigation Scheduling for Tomato (<i>Solanum Lycopersicum</i>) Crop Under Rain Shelter for Effective Irrigation Water Management

Tomato (<i>Solanum Lycopersicum</i>) is a staple vegetable and important cash crop in Ethiopia. However, extreme weather events and recurrent droughts affected the yield and quality of tomatoes and their marketability. Irrigation can mitigate the negative impacts of drought in a water-scarce area. Since water is scarce, it needs effective management for water productivity improvement and sustainable production. Effective management of water could be attained by irrigation scheduling, i.e, giving the required amount of water at the right time (when and how much) for the crop. Therefore, the objective of the current study was to determine the optimal depletion level of tomato for irrigation scheduling to effectively manage irrigation in a control environment under a rain shelter. The experiment was conducted at the Jimma Agricultural Research Center on the tomato Galilama variety under a rain shelter. Randomized Complete Block Design (RCBD) with three replications was used. Five treatments of different depletion levels were randomized in the plots. All agronomic and crop management practices were applied to all treatments in accordance with the recommendations made for the crop. Tomato yield and growth parameters data were recorded, and the treatments were compared based on yield and growth parameters using the SAS 9.2 software. The result reveals that, the plant height, biomass, and tomato yield were not affected statistically (p > 0.05) due to the depletion level of water under the rain shelter. However, the maximum plant height and maximum yield were recorded at 60% of the available soil moisture depletion level, and the maximum biomass was recorded at 120% of the available soil moisture depletion. The different levels of depletion significantly influenced the root length, biomass, and water productivity of tomatoes. The statistical analysis result showed that the maximum root length of 31.05 cm was recorded at a 120% available soil moisture depletion level (ASMDL4). The maximum agricultural water productivity was obtained at 60% available soil moisture depletion level (ASMDL1). It could be recommended that 60% of the available soil moisturedepletion level was the best for yield improvement, water productivity and water management under the rain shelter for tomato production.