Abstract: 【Objective】 The objective of this study was to investigate whether or not the ozone (ozone, O₃) could effectively reduce the negative effects of the swelling agent (N-2-chloro-4-pyridine benzene-N'- phenyl urea, CPPU) on kiwifruit, which would provide useful information for using of CPPU on the market for the storage.【Method】First, the Qinmei kiwifruit was treated with 20 mg·L^-1 CPPU in the growing season, then treated with 10, 40, 70 mg·m^-3 ozone respectively in postharvest. The material contents in kiwifruit of methionine (methionine, Met), S-adenosyl methionine (S-adenosyl methionine, SAM), 1-aminocyclopropane-1- carboxylic acid (1-aminocyclopropane-1-carboxylic acid, ACC) and the related metabolic enzyme activity of ACC synthase (ACC synthase, ACS) and ACC oxidase (ACC oxidase, ACO) were studied. 【Result】The decreasing rate of Met, SAM and activity of SAM synthase, ACS, ACO under CK (without the use of CPPU and O₃ treatment as CPPU control CK group) during storage was lower than that under CK1 (using CPPU without using O₃ treatment for ozone treatment control CK1 group). At 60 days after kiwifruit storage, the contents of Met under CK1 and each treatment group (10, 40 and 70 mg·m^-3 ozone) were 1.36, 2.62, 4.41 and 2.60 mg·(100 g)^-1, respectively. The contents under O₃ treatment was significantly higher than that under CK1 (P＜0.05). The contents of SAM under CK1 and 40 mg·m^-3 O₃ group were 15.48 mg·(100 g)^-1 and 20.73 mg·(100 g)^-1, respectively (P＜0.05), but the contents under CK1 10 mg·m^-3 O₃ treatment, and 70 mg·m^-3 O₃ treatment no significant difference (P＞0.05). The ACC contents under CK1 and each treatment group (10, 40 and 70 mg·m^-3 ozone) were 0.068, 0.059, 0.038 and 0.055 nmol·g^-1, respectively. There were significant differences (P＜0.05) between 40, 70 mg·m^-3 O₃ treatments and CK1. The ACS activities in CK1 group and each treatment group (10, 40and 70 mg·m^-3) were 0.084, 0.069, 0.054 and 0.080 nmol·(g·h)^-1, respectively. The peak of ACO activity was 0.062, 0.046, 0.029 and 0.051 nmol·(g·h)^-1, respectively. There was significant difference between the treatment and the CK1 (P＜0.05). The peak values of ethylene in CK1 and each treatment (10, 40, and 70 mg·m^-3 ozone) were 18.42, 15.99, 9.86 and 11.69 μL·kg^-1·h^-1, respectively, and the peak of respiration was 18.77, 16.15, 12.24 and 15.48 mg·kg^-1·h^-1, respectively.【Conclusion】CPPU increased the kiwifruit ethylene production and accelerated fruit softening, had a negative impact on kiwifruit storage, while O₃ could effectively inhibit the ethylene metabolism of kiwifruit. O₃ treatment could effectively slow down the kiwifruit ripening due to the use of CPPU.

Key words: ozone, CPPU, kiwifruit, ethylene metabolism, respiration rate