Antioxidant pool optimization in Carthamus tinctorius L. leaves under different NaCl levels and treatment durations

Safflower (Carthamus tinctorius L.) leaves are a good source of natural antioxidants, but their content is highly related to the plant response to NaCl constraint; therefore, optimizing culture conditions is required to improve leaf antioxidant accumulation while maintaining acceptable biomass production under stressful conditions. Leaves from plants grown at (0, 25, 50, and 75 mM NaCl) for three treatment durations (7, 15, and 30 days) were studied. NaCl concentrations and treatment durations for optimal biomass and biomolecules production were concluded. After 30 days of treatment, 25 mM NaCl enhanced total AsA leaf accumulation, while glutathione, soluble protein accumulation as well as SOD and GR activities were promoted at 75 mM NaCl. Non-significant changes were found for MDHAR and DHAR activity, added to, a very low level of reduced AsA, suggesting that ascorbate recycling was not an efficient system in safflower leaves under salinity. Our study demonstrates that C. tinctorius tolerates NaCl stress due to the complementary roles of powerful antioxidant molecules, such as ascorbate (for short-term treatments), glutathione (for long-term treatments), and increased SOD and GR activities.