Simulation of the effect of deficit irrigation schemes on tomato crop production using aquacrop model

The current study investigates the possablities to improve irrigation water productivity of tomato crop, as one of the most important vegetable crops in Egypt, by applying different  deficit irrigation scheme . Field experiment was carried out at the Vegatable Farm of the Faculty of  Agriculture- Ain Shams University, througthout two seasons 2015/2016 and 2016/2017, on tomato crop under drip irrigation system. Five irrigation treatments, included: (i) 100% ETc [T100], (ii) Application of deficit irrigation level 80% ETc at all crop growing stages [TC80], (iii) Application of deficit irrigation level 80% ETc at initial and maturity crop stages only [TS80], (iv) Application of deficit irrigation level 60% ETc at all crop growing stages [TC60], (v) Application of deficit irrigation level 60% ETc at initial and maturity crop stages only [TS60]. The results showed that, among the investigated deficit irrigation schemes, applying diffecit irrigation schemes of 80% ETc could reduce the amount of the irrigation water by 20% when it was applied at all crop growing stages, coupled with a yield reduction of about 17%, and a slight increase in water productivity [WP] (dividing dry matter of the yield to the ETc) by about 2%. Whereas the same deficit level could save about 16% of the applied water when it was applied only at initial and maturity growth stages, and decreased the crop yield by 5%, which gave the highest WP of 2.15 kg/m3, compared to the other investigated irrigation treatments. Regarding the AquaCrop model simulation, the results showed that, considering good calibration process, AquaCrop model revealed a very good performance in simulating the tomato crop biomass, and yield. This could encourage addressing AquaCrop model as a good tool that can be used with a high degree of reliability in practical management, strategic planning of irrigation, and water limited conditions in Egypt.