Effect of some irrigation systems on water stress levels of Washington navel orange trees

Abstract Background This experimental study was conducted during two successive seasons 2021–2022 on 10-year-old Washington navel orange trees ( Citrus sinensis ) budded on sour orange rootstock ( Citrus aurantium ) under sandy loamy soil conditions in Belbeis district, Sharkia Governorate, Egypt. This experimental study was conducted to compare some irrigation systems with different water stress levels on Washington navel trees and to determine the best system in terms of irrigation water use efficiency using different irrigation systems (drip and micro-sprinklers) under different levels of water supply (100, 80, and 60% of ETc, i.e., the estimated water requirements of crops). Results The included data demonstrated that irrigation water amounts can be reduced by 20% for Washington navel trees, while maintaining production, with the possibility of increasing by using micro-sprinkler irrigation systems. In summary, water use efficiency increased with micro-sprinkler irrigation systems under ETc 80%, which resulted in 2.57 and 2.67 kg of fruit per cubic meter of irrigation water in the first and second seasons, respectively. Conclusion The results of the present study showed that using ETc 80% combined with micro-sprinklers irrigation system had a high economic return through increasing total yield, water use efficiency, and water unit return (WUR) which reached to 10.26 EGP/one cubic meter of irrigation water and using less water irrigation amount by 20% at the same time. Thus, we recommend applying the treatment of ETc 80% combined with micro-sprinklers irrigation system to Washington navel orange trees budded on sour orange rootstock to gain a high economic return.