The modelling of tomato crop response to the climate change with different irrigation schemes

The inequality between available water supplies and growing water demand from diverse sectors, as well as the predicted climate changes are putting significant pressures on Egypt’s food security. There is a nation-wide demand for new scientifically proven on-farm practices to boost water productivity of major food crops. The objective of this study was to explore the use of various deficit irrigation schemes to improve water productivity (WP) of tomato cultivated in Egypt under distinct climate change scenarios, RCP4.5 and RCP8.5, in three time-steps of the reference period (2006-2016), 2030s, and 2050s. The AquaCrop model was used to simulate the influence of climate change on the tomato crop, as well as two deficit irrigation application schemes for the full growing season and the regulated application for the initial and maturity crop stages. With the same irrigation method, the predicted WP increased in a general pattern across all climate change scenarios. The combination of irrigation schedule with the 80% deficit irrigation can enhance WP near the optimum level (approximately 2.2 kg∙m-3), especially during early and mature stages of the crop, saving up to 16% of water. The results showed that the expected temperature rise by 2050s would reduce the crop growth cycle by 3-11 days for all irrigation treatments, resulting in a 1-6% decrease in crop evapotranspiration (ETc) and affecting the dry tomato yield with different patterns of increase and decrease due to climate change.