Effect of auxin foliar application on seed yield and fatty acids composition of two safflower genotypes under late-season drought

To assess the response of two safflower genotypes to auxin foliar application under late-season drought stress using a factorial split-plot experiment with the randomised complete block design, a two-year experiment (2016-2017 and 2017-2018) was conducted in Iran. The watering regime as specified in two levels including, regular irrigation and drought stress in main plots and two safflower genotypes and auxin foliar application in two levels including non-foliar application (control) and auxin foliar application at a concentration of 30 ppm were categorised in subplots. Drought stress at the seed filling stage reduced the safflower seed and oil yield. Moreover, a significant drought-induced decrease in linoleic acid, palmitic acid and behenic acid content, as well as an increase in oleic acids, was observed in two safflower genotypes. Among two safflower genotypes, the early maturing genotype less affected by drought and Goldasht had higher seed yield than the Padideh by 814 kg/ha, respectively. Auxin foliar application alleviates the adverse effects of drought, which led to an 18% increase in seed yield and components. However, the auxin application had no effect on the safflower seed oil content but palmitic acid content was affected by auxin foliar application. Generally, safflower along with auxin application can be recommended to develop safflower cultivation in semi-arid areas.