[Effects of exogenous salicylic acid on seed germination and physiological characteristics of Coronilla varia under drought stress.]

This research investigated the effects of different concentrations (0, 0.5, 1.0, 2.0 mmol·L-1) of salicylic acid on the seed germination and physiological characteristics of legume forage Coronilla varia (cultivar 'Lvbaoshi') under PEG-6000 (concentration 8% and 12%) simulated drought stress. The results showed that under drought stress, 0.5-1.0 mmol·L-1 salicylic acid significantly increased germination percentage, germination vigour, germination index, vitality index and bud length of C. varia. Under the stress of 12% PEG, the dry mass of C. varia seedlings processed by 1.0 mmol·L-1 salicylic acid was significantly higher than that under drought stress. 0.5-1.0 mmol·L-1 salicylic acid processing significantly increased proline, soluble protein content, the activities of catalase, peroxidase and superoxide dismutase of C. varia seedlings under drought stress, but cell electrolyte permeability, H2O2 content and O2-· production rate of seedlings were significantly decreased. 1.0 mmol·L-1 salicylic acid produced the best results. When the concentration of salicylic acid was beyond 2.0 mmol·L-1, no mitigation effect was observed on the seed germination and growth of seedlings under drought stress. It was concluded that salicylic acid at appropriate concentrations could effectively improve osmotic regulation, antioxidation and mitigate the damage of drought stress so as to promote the growth of C. varia seedlings.