Abstract: To investigate the effects of disease inducing treatment on phenolic metabolism of melon leaves and the relationship to leaf disease resistance，two melon cultivars（‘Yindi’and‘Kalakesai’）of different disease resistance were employed. Benzo-1, 2, 3-thiadiazole-7-carbothioic acid S-methyl ester （BTH），salicylic acid（SA）and Nano silicon（SiO2）were sprayed five days before inoculation with spore suspension of Sphaerotheca fuliginea，phenolic compound contents and relative enzyme activities were determined as the indicators. The activities of phenylalanine ammonia lyase（PAL），peroxydase（POD），polyphenol oxidase（PPO），and the contents of total phenols，chlorogenic acid，flavonoids in melon leaves increased significantly after spraying with BTH，SA and/or inoculation of Sphaerotheca fuliginea spore suspension. SiO2 spraying did not show such inducing effect. The contents of phenolic compounds and the activities of relative enzymes in the disease resistant cultivar were higher than those in the susceptible cultivar after inducing treatment. The results suggest that one of the possible mechanisms of BTH and SA spraying on induced resistance of melon leaves is via increased contents of phenolic compounds and enhanced activities of phenol-related enzymes.

Key words: Cucumis melo, powder meldew, BTH, SA, nano silicon, phenol metabolism