ABSTRACT
Objective: To study the effects of exogenous salicylic acid (SA) on the seed germination and seedling growth of Pogostemon cablin under salt stress and the optimal concentration of SA for alleviating the salt stress. Methods: Under salt stress simulated by 50 mmol/L NaCl solution, P. cablin was used to investigate the effects of exogenous SA on the seed germination and seedling growth with paper media. The germination energy (GE), germination rate (GR), germination index (GI), vigor index (VI), seedling length (SL), root length (RL), seedling fresh weight (SFW), seedling dry weight (SDW), and contents of soluble protein (SP) and chlorophyll in the leaves were determined, and the relative salt-damage rate of these indexes was analyzed. Results: The seed germination and seedling growth of P. cablin were significantly inhibited under 50 mmol/L NaCl stress. Compared with NaCl stress, the seed germination and seedling growth were improved when SA were 0.10 and 0.25 mmol/L, while reduced when SA was 0.50 mmol/L. GE, GR, GI, VI, SL, RL, SFW, SDW, and contents of SP and chlorophyll were significantly improved by 46.02%, 27.45%, 30.16%, 92.63%, 39.80%, 47.94%, 26.48%, 18.85%, 15.94%, and 14.70% with 0.25 mmol/L SA, as well as MDA content was significantly reduced by 18.35%. Conclusion: SA could improve the ability of the seed germination and seedling growth of P. cablin to adapt the environment and alleviate the inhibitory effects of salt stress. Among all the treatments, the optimal concentration of SA is 0.25 mmol/L.