Influence of Seed Priming on Seed Yield, Oil Content and Fatty Acid Composition of Safflower (Carthamus tinctorius L.) Grown Under Water Deficit

Safflower oil is a rich source of omega-3 fatty acids that is important for health. Drought stress can severely decrease the productivity and oil quality of safflower. Thus, in order to study the effect of hydropriming and melatonin-seed-priming on fatty acid composition and yield of Safflower under water deficit conditions a field experiment was carried out as split-factorial in a randomized complete block design with four replicates during 2017 and 2018 growing seasons. The oil concentration of the safflower seeds was determined by soxhlet extraction method. Fatty acids of safflower's oilseed were transformed to their methyl esters (FAME), and a gas chromatograph equipped with a flame ionization detector (FID) was used for determination of fatty acids. The results indicated that melatonin-seed priming increased grain yield, HI and oil yield of safflower under drought condition. Drought stress led to a significant decrease in oil yield, and recently harvested seeds had higher oil yield across both years. The highest amount of oil yield was obtained by hydropriming on seeds which had been stored for 8 years, and recently harvested seeds with 576.50 and 645.57 kg.ha(-1), respectively under no-stress condition. Melatonin-seed-priming improved the oil quality of safflower under drought with an increase of unsaturated fatty acids of safflower especially omega 6 and omega 3. Melatonin-seed priming increased the amount of n-ary sumation PUFA, n-ary sumation UFA/ n-ary sumation SFA, P/S and DBI across both years in comparison with unprimed seeds. Seed priming improved the quality of oil and productivity in both recently harvested and stored seeds. It can be concluded that melatonin-seed priming improved the productivity, oil content and composition especially in stored seeds and under drought stress.