Abstract
Water availability is the most important key factor affecting sunflower productivity and its oil quality. This study investigated the effect of drought stress on sunflower fatty acids and its effects on grain yield and related components. Thirteen sunflower hybrids were evaluated as randomized complete block design with three replications under normal and drought stress conditions in Karaj, Iran, during 2 years (2019 and 2020). Drought stress was imposed by water withholding during the reproductive stage. Drought stress accelerated the maturity of sunflower and caused a reduction in grain yield (30%), grains weight (11%), and grain numbers/head (22%) compared with normal irrigation. Means of grain yield were 2.7 and 1.8 t/ha under normal and drought stress conditions respectively. Grain numbers/head had higher correlation with grain yield than grains weight under both conditions. Among the fatty acids, the contents of palmitic and linoleic acids were increased (11% and 3%, respectively) while stearic and oleic acids were decreased (6% and 11%). The results indicated that sunflower hybrids benefit from the escape strategy differentially to adapt drought stress condition. However, this adaptation changes sunflower fatty acid profile that reduces grain yield and quality of sunflower oil in Karaj conditions in Iran. In order to achieve the higher yields and higher oil quality, it is necessary to avoid drought stress in sunflower production fields.