Effect of glycine betaine and salinity on photosynthetic pigments and ion concentration of safflower

The influence of exogenous application of glycine betaine (GlyBet) was examined on photosynthetic pigments and ions concentration of safflower under salinity stress conditions. The experiment was performed in a randomized complete block design arranged as a factorial with three replications. Salinity treatments (0, 50, 100, and 150 mM) were applied using sodium chloride (NaCl). GlyBet (0, 10, 30, and 60 mM) sprayed onto leaves of safflower. The results showed that an increase in salinity levels led to an increase in Na+ content and Na^+/K^+ ratio and a reduce in shoot and root fresh weight, chlorophyll, carotenoid, photosystem II (PS II) activity , K^+, and Ca^2+ contents. In all stress levels, foliar application of 30 and 60 mM GlyBet led to an increase in chlorophyll a, b and total chlorophyll, carotenoids and PS II activity than control. Also, in all salinity levels, foliar application of GlyBet reduced Na^+ content and Na^+/K^+ ratio of the plants and increased their K^+ and Ca^2+ contents. These results suggest that the application of 30 and 60 mM GlyBet under salt stress conditions had the largest effect on photosynthetic pigments, PS II activity, and K^+ and Ca^2+ contents of safflower.