Foliar Spray of Stigmasterol Regulates Physiological Processes and Antioxidant Mechanisms to Improve Yield and Quality of Sunflower Under Drought Stress

Abstract Drought stress is an unavoidable challenge limiting plant production and quality. Stigmasterol a potential compound for protection improvement productivity under drought. Thus, the effects of using stigmasterol as exogenous treatment on improving growth sunflower grown drought were studied. A pot experiment was carried out at two summer seasons, foliar 0, 100, 200, 300 mg L −1 plants different irrigation levels 80% 50% water requirement (WIR). (50% WIR) provoked significant reductions in yield components; percentages decrease head diameter reached 26.55%, circumference 26.05%, seed weight per 36.26%, 100 29.61%, via decreasing photosynthetic pigments indole acetic acid while elevating hydrogen peroxide (H 2 O ), lipid peroxidation (MDA), membrane leakage, lipoxygenase activity, some antioxidant compounds, enzymes, osmolytes. has promotive effect through pigments, acid, non-enzymatic, enzymatic antioxidant, osmolytes, it decreased H , MDA, thus, Moreover, improves economic importance oil. About 200 most effective concentration parameters, causes 19.84% 25.29% 26.72% 33.95% WIR, respectively. improved normal conditions could overcome reduced impact by development physiological attributes.