Abstract: Objective: To investigate the effect of preharvest benzothiadiazole (BTH) spraying on the softening of harvested Agaricus bisporus during cool storage, and to explore the underlying mechanism. Methods: A. bisporus (cv. A15) was sprayed with BTH at 200 mg/L at the primordia stage and evaluated for texture properties and mass loss rate, the contents of chitin, cellulose and protein and related enzyme activities during postharvest cool storage. Results: Pre-harvest BTH spraying significantly reduced the mass loss of A. bisporus during cool storage, by 34.22% relative to the control group on day 8. BTH spraying significantly improved the firmness, flexibility, chewiness and gumminess of A. bisporus, decreased the activities of chitinase and cellulose, increased the contents of chitin and cellulose, reduced the activities of neutral, alkaline and acid proteinase at harvest and during cool storage (P < 0.05). In addition, BTH spraying delayed the degradation of protein. Correlation analysis indicated that the firmness, flexibility, chewiness and gumminess were significantly positively correlated with the contents of chitin, cellulose and protein, but significantly negatively correlated with the mass loss rate of A. bisporus (P < 0.01). Conclusion: Preharvest BTH spraying can significantly inhibit the softening of A. bisporus during cool storage, and the underlying mechanism may be closely related to reducing the activity of cell wall-degrading enzymes and postharvest mass loss rate.

Key words: benzothiadiazole; preharvest spraying; Agaricus bisporus; softening; cell wall degrading enzyme; mass loss rate