Evaluation of photosynthetic pigments, antioxidant enzyme activity and seed yield of safflower cultivars under cutting off irrigation

In order to investigate the effect under late season cutting off irrigation on biochemical properties and yield of safflower cultivars a split factorial experiment in a randomized complete block design was conducted in three replicates at College of Agriculture and Natural resources of Darab, Shiraz University during 2017-2018 growing season. The main factor was irrigation regime in three levels included of normal irrigation, cutting off irrigation in the middle of the flowering, and in the early seed filling stages and sub factor was safflower cultivars including Padideh, Goldasht, Faraman and Isfahan local. Cutting off irrigation in flowering stage decreased 30.37% of chlorophyll a and 25.8% of chlorophyll b, and increased 15.38% carotenoid, 23.38% of catalase activity and 34.94 % of peroxidase activity, which in Goldasht cultivar was more than the other cultivars. Under cutting off irrigation at flowering and seed filling, the highest seed yield was obtained in Goldasht cultivar as 132 and 150.5 g/m2, respectively. Overall, cutting of irrigation at flowering and seed filling stages reduced grain yield by 32.3 and 19.93%, respectively. Under cutting off irrigating, seed yield with chlorophyll a content (r=0.77**), chlorophyll b (r=0.86**), carotenoid (r=0.74**), catalase (r=0.71**), peroxidase (r=0.72**), and harvest index (r=0.83**) had positive and significant correlation. In addition, Goldasht cultivar of safflower could by increasing photosynthetic pigments and enzyme activity under water deficit in late season obtained the more seed yield compared to other cultivars.