Impact of Salinity on Growth Performance and Antioxidant Defense in Safflower (Carthamus tinctorius L.)

Salt stress represents a major abiotic constraint affecting global crop productivity, particularly in arid and semi-arid environments. Safflower (Carthamus tinctorius L.) is known for its moderate salt tolerance; however, cultivar-specific physiological and biochemical mechanisms remain insufficiently characterized. This study aimed to evaluate the effects of increasing salinity levels (0, 5, 10, 15, and 20 dS /m EC) on morphological growth and antioxidant responses of the Turkish Hasankendi safflower cultivar under controlled greenhouse conditions. A completely randomized design was applied, and morphological traits (plant height, root length, stem diameter, leaf number, fresh and dry weights) together with biochemical parameters (total antioxidant capacity, DPPH radical scavenging activity, total phenolics, flavonoids, and tannins) were analyzed. Increasing salinity led to significant reductions in plant height (45%), root length (62%), and dry biomass (86%), while total phenolic and flavonoid contents rose by 134% and 303%, respectively, compared with the control. The results indicate that Hasankendi exhibits a moderate tolerance to salinity through the activation of non-enzymatic antioxidant mechanisms, particularly the synthesis of phenolic and flavonoid compounds that mitigate oxidative damage. These findings provide valuable insights into the biochemical adaptation strategies of safflower under salt stress and highlight Hasankendi as a promising genetic resource for improving both stress tolerance and antioxidant potential in breeding programs.