Effects of three exogenous substances on the salt tolerance of creeping bentgrass

In this study, we examined the ability of three exogenous substances to alleviate salt stress in the creeping bentgrass (Agrostis stolonifera) cultivar ‘L-93’. A pot experiment was conducted to investigate the effects of potassium sulfate (K₂SO₄), ascorbic acid (AsA), and glycine betaine (GB) on the turf quality (TQ), relative water content (RWC), electrolyte leakage (EL), malonaldehyde (MDA) and ion contents, and antioxidant enzyme activity of the creeping bentgrass under salt stress conditions. Salt stress significantly reduced the TQ, RWC, and antioxidant enzyme activity of ‘L-93’ (P < 0.05) and significantly increased the EL and MDA contents (P < 0.05), resulting in an ion imbalance. However, the application of K₂SO₄ and AsA alleviated the negative effects of salt stress, significantly increasing RWC (P < 0.05), significantly reducing EL and the accumulation of Na⁺ in leaves (P < 0.05), and increasing the K⁺ content of leaves, thereby reducing the Na⁺/K⁺ imbalance. In addition, exogenous spraying of K₂SO₄ and AsA improved the catalase (CAT) activity in and salt tolerance of the creeping bentgrass, while also enhancing its antioxidant capacity, under salt stress. Exogenous GB application significantly increased CAT activity and decreased Na⁺/K⁺ values in creeping bentgrass leaves (P < 0.05) but had no significant effect on TQ or MDA content (P > 0.05); the overall effect was inferior to that of K₂SO₄ and AsA.