13. Response of Vegetable Crops to Irrigation Regimes Using Saline Waters

Field studies were conducted to examine the response of potato, carrot, fava bean, and pepper to irrigation regimes using saline water in a commercial farm. The irrigation regimes were full (FI100) and deficit (DI70) irrigated with levels of 100 and 70% of crop evapotranspiration (ETc) when the readily available water, 40% of total available water (TAW), in the FI100 treatment was depleted, and traditional farmer practice (FM). For all experiments, the largest soil salinity values were observed under the farmer treatment compared to the FI100 and DI70 treatments. The highest mean yields of potato (24.4–27.5 t/ha), carrot (28.4–30.3 t/ha), fava bean (19–21.3 t/ha), and pepper (10.9–12.5 t/ha) were recorded for the FI100 treatment. Compared with FI100, significant reductions in potato, carrot, fava bean, and pepper yields were observed under the DI70 treatment, with only a few exceptions, resulting from a reduction in yield components. The farmer’s method not only caused significant reductions in yields but also resulted in an increase of water usage of 14–22%, 18–21%, 12.5–19%, and 13.9–15.5% for potato, carrot, fava bean, and pepper, respectively, and increased soil salinity. Water productivity (WP) values reflected the differences in yields and varied between 4.3 (farmer) and 13.7 kg/m³ (DI70) for potato, 4.4 and 11.7 kg/m³ for carrot, 4.8 and 13.7 kg/m³ for fava beans, and 0.8 and 2.6 kg/m³ for pepper across different years and treatments. The FI100 scheduling technique with variable water amounts was more efficient and provided significant advantage in yield, water productivity and net income, compared to the FM treatment in potato, carrot, fava beans, and pepper yields under arid environment. FI100 scheduling technique is suggested for vegetable crops in the arid environment. Under water restriction conditions, adoption of the DI70 strategy allows 30% water saving compared with FI100 with relatively small impact on soil salinity and some reductions in yield and net income.