Responses of growth and antioxidant systems in Carthamus tinctorius L. under water deficit stress

An investigation was carried out to find out the extent of changes occurred in two safflower (Carthamus tinctorius L.) cultivars in response to water deficit stress. Two safflower cultivars namely IL.111 and Isfahan were used for the study. Thirty days after sowing, plants were grown under soil moisture corresponding to 100, 85, 70 and 55% field capacity for next 30 days. Water deficit treatments significantly decreased the shoot length, shoot dry matter, root dry matter, relative growth rate, leaf relative water content (LRWC) and leaf water potential (I-W), whereas root length, root-to-shoot ratio, lipid peroxidation and antioxidant compounds such as ascorbic acid (AA), alpha-tocopherol (alpha-Toc) and reduced glutathione (GSH) and superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and peroxidase (POX, EC 1.11.1.7) activities were increased. Water deficit stressed plants maintained higher levels of compounds and scavenging enzymes. Significant differences were observed between cultivars and irrigation levels treatments. The cv. IL.111 could be considered more tolerant to water stress than cv. Isfahan, registering greater biomass, LRWC and leaf water potential (I-W), associated with high antioxidant activity.