RESPONSE OF SUNFLOWER CROP TO DIFFERENT LEVELS OF SOIL MOISTURE DEPLETION

The amount of water utilized by the plant has a significant impact on its yield. In this regard, yield response factor (Ky) permits measuring yield decline as a function of evapotranspiration. As a result, the purpose of this study was to calculate Ky for the sunflower crop grown in North Nile Delta, Egypt and to calculate economic water productivity. Seasons 2021 and 2022 were studied. The experiment used a complete randomized block design with three replicates. W1 (50-55%), W2 (55-60%), and W3 (60-65%) maximum allowable depletion of available soil moisture (MAD of ASW) treatments were used. In total, the average two seasons (0.52 and 0.61) found for sunflower crop under W2&W3, respectively, demonstrated its strong sociability to water deficit. Its yield is substantially impacted by water availability, with average 0.65 & 0.47% loss in yield for every 1% reduction in evapotranspiration with w2 and w3 treatments, respectively. The treatment without stress, w1 (50-55% MAD of ASW), yielded the highest grain yield. However, after considering water and irrigation costs, it could conclude that other stressed treatments, W2&W3, were more cost-effective.