Mitigating effect of exogenous 2, 4-epibrassinolide on the inhibition of oat seed germination under salt stress

Oat seeds of Jiayan 2 and Qingyin 2 (Avena sativa) were used as materials to study the osmosis of exogenous 2, 4-epibrassinolide (EBR) in the germination, seedling growth, and germination of oat seeds under salt stress by adding exogenous 2, 4-Epibrassinolide (EBR) with 100 mmol·L^–1 NaCl. The aim of this study was to clarify the physiological mechanism of exogenous BRs regulating oat seed germination under salt stress. The results showed that: 1) with 100 mmol·L^–1 NaCl stress, the osmotic adjustment ability and antioxidant enzyme (superoxide dismutase, SOD; ascorbate peroxidase, APX; guaiacol peroxidase, GPX) activity of Jiayan 2 and Qingyin 2 oats during seed germination significantly decreased, and the level of reactive oxygen species (·O₂^–, ·OH, H₂O₂) and MDA content significantly increased, while seed germination and seedling growth were significantly inhibited. 2) Adding 0.01 μmol·L^–1 EBR could significantly alleviate the inhibiting effect of 100 mmol·L^–1 NaCl stress on oat seed germination. Compared with NaCl stress in the NaCl + EBR treatment, the activity of proteolytic enzymes significantly decreased, the content of soluble protein, soluble sugar, free proline significantly increased, antioxidant enzymes (SOD, APX, GPX, and CAT) significantly increased, and reactive oxygen species (·O₂^–, ·OH, H₂O₂) significantly decreased. The germination potential, germination rate, germination index, and vigor index of the seedlings significantly increased, while the seedling height, root length, dry weight, and root activity of the seedlings significantly increased. The results showed that exogenous BRs could improve osmotic regulation and antioxidant system activity during the germination of oat seeds under salt stress, inhibit the accumulation of reactive oxygen species and membrane lipid peroxidation products, promote the germination of oat seeds and the growth of seedlings, and improve the salt tolerance of oat seeds during germination.