Physiological regulation of brassinosteroids on seed germination and seedling growth in Lolium perenne in response to salt stress

The physiological effect of 2, 4-epinebrinolide (EBR) on seed germination and seedling growth in Lolium perenne under salt stress was studied. The results showed that the germination rate, germination potential, activity index, plant height, fresh weight, and root activity of ryegrass seeds were improved by under salt stress treatment with exogenous 0.01 μmol·L⁻¹ EBR. The α-amylase activity of the ryegrass seeds was enhanced during germination. During the seeding growth stage, the activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione peroxidase (GPX) in ryegrass seedlings exogenous 0.1 μmol·L⁻¹ EBR treatment under salt stress significantly increased (P < 0.05), while the content of malondialdehyde (MDA) significantly decreased. The soluble sugar, soluble protein, and chlorophyll contents were significantly elevated (P < 0.05). These results indicated that exogenous 0.01 μmol·L⁻¹ EBR treatment alleviated the inhibitory effect of 100 mmol·L⁻¹ NaCl and 150 mmol·L⁻¹ NaCl stress on seed germination, while exogenous 0.1 μmol·L⁻¹ EBR alleviated the damage of 250 mmol·L⁻¹ NaCl stress on seedling growth. The results of this study provide a theoretical basis for the application of ryegrass to saline-alkali land.