Abstract:To reveal the response mechanism of salicylic acid (SA) to induced resistance of camellia, the effect of SA to Pestalotiopsis guepinii (Desm.) Stey was determined using the agar plate method. The results showed that the concentration of SA at 0-5 mmol/L had no inhibition effect to the growth of the pathogen. The defense enzymes such as speroxidase (POD), polyphenol oxidase (PPO), catalase (CAT) and phenylalanine amonnialyase (PAL) had different responses to the disease resistance of camellia induced by spraying SA. The enzymes treated with both inducement and challenge inoculation were faster than those only treated with inducement in the plants. The activities of POD, PPO, CAT, and PAL with different concentrations of SA inducement and challenge inoculation had the positive correlations with the concentration of SA. The correlation analysis showed that the CAT activity had significant correlation (r=-0.9730) with infection index. However, the rest enzymes didn’t show significant correlations with infection index, but still had high correlation coefficients except PPO, indicating that POD and PAL played important roles in the induced resistance.