| Muskmelon is one of important special products in Gansu. However, postharvest decay is serious. Some pathogens infect young fruit as latent infection during growth and development, which courses a difficulty of control decay. BTH at 100mg/L or Harpin at 50mg/L was sprayed 4 times to melons (cv. Yindi) in the field. The spray time was at 1 week before flowering, young fruit period, fruit enlarging period, and netting period. The results indicated as below: 1. The latent infection rate of fruit was reduced significantly with BTH and Harpin treatment. The latent infection rate decreased with increasing of spraying times. The four times of spraying showed the best effective control. The latent infection rate of BTH or Harpin was 23.53% and 25% compared with the control. 2. There was a difference between latent infection rate of A. alternate and Fusarium sp. after treatment with elicitors. BTH or Harpin had better control on A. alternate. 3. There was also a difference on latent infection rate of different part of fruits after treatment with elicitors. BTH or Harpin had the most effective control for the latent infection rate of fruit top. 4. BTH or Harpin. Treatment increased POD and CHT activities of fruit. POD activity was higher 1.81 and 2.08 times than the control after 4 times spraying with BTH or Harpin at fruit ripening period. CHT activity was higher 1.96 and 2.93 times. There was no difference on the bands of POD isoenzyme, however, activities of some bands were enhanced. 5. The preformed antifungal compounds and phenolic compounds were increased in fruit after treatment with BTH or Harpin. By using ethanol-dichlormethane and column-chromatography, the results showed: the kinds and content of preformed antifungal compounds were increased with increasing of spraying times after TLC and bioassay identification. 6. Tissues of cortex showed more tightness. Ligni, spile and callose accumulated significantly in cells of cortex after treatment with BTH or Harpin. |
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