Effect of iron application on enzymatic activity, grain yield and oil content of safflower under water deficit conditions

To study the effect of soil and foliar application of Fe-EDDHA on the activity of some antioxidant enzymes, grain and oil yield in safflower under water deficit conditions, an experiment was conducted in research field of faculty of agriculture, Shahed University, Tehran, Iran, in 2008 cropping season. The experimental design was split-plot arrangement in randomized complete blocks with four replications. Main plots consisted of two levels of irrigation; 1: Full irrigation (irrigation after reaching to 50% soil moisture depletion of field capacity), 2: No irrigation after flowering stage (irrigation after reaching to 75% soil moisture depletion of field capacity). Sub plots were eight levels of Fe-EDDHA, that four levels of it were soil application (0, 50, 100, 150 kg.ha-1 of Fe-EDDHA) and four levels were foliar application (foliar application of water and 1, 2, 3 mg.l-1 of Fe-EDDHA) on spring safflower cv. IL 111. Results showed that soil application under drought stress conditions increased antioxidant enzymes activity of Catalase (CAT), Ascorbate Peroxidase (APX), Polyphenol Oxidase (PPO) and Superoxide dismutase (SOD). However, Peroxidase (POX) activity increased with foliar application of Fe-EDDHA. Effect of drought stress and Fe-EDDHA was significant on harvest index, grain and oil yield of safflower. The highest grain yield under drought was 3176.5 kg.ha-1 and 3133.6 kg.ha-1, obtained with soil application (50 kg.ha-1 of Fe-EDDHA) and foliar application (1 mg.l-1 of Fe-EDDHA), respectively. The highest grain yield in full irrigation was, 3765.7 kg.ha-1 and 3731.3 kg.ha-1 obtained with foliar application (2 mg.l-1 of Fe-EDDHA) and soil application (150 kg.ha-1 of Fe-EDDHA), respectively. The highest oil grain yield under drought stress, 1440.2 kg.ha-1, was obtained from soil application (50 kg.ha-1 of Fe-EDDHA). However, the highest oil yield in full irrigation, 1699.6 kg.ha-1, was obtained from foliar application (2 mg.l-1 of Fe-EDDHA). In conclusion, the application of Fe-EDDHA could increase antioxidant enzymes activity and led to improved grain and oil yield of safflower under drought stress conditions.