Abstract:Objective: The effect of low temperature conditioning(LTC) combining with exogenous ethylene on the sugar metabolism of postharvest kiwifruit was studied. Methods: The kiwifruit was placed at four temperatures: 0, 4, 8, 12 ℃ for 3, 5, 7 day, respectively, and then ripened at room temperature (25 ℃) with ethylene. The kiwifruit directly ripened at room temperature was as control group (CK). The soluble sugar content, monosaccharide content (glucose, fructose and sucrose), starch content, amylase activity, and sugar metabolism enzymes activities in 12 treatment groups and CK were determined. Results: LTC treatment could increase the soluble sugar content and starch degradation rate, maintain high amylase activity in kiwifruit. Neutral invertase (NI) and sucrose phosphate (SPS) enzyme activities were maintain effectively. However, the effect of LTC on AI and SS enzymes activities was not significant. Through principal component analysis (PCA) and cluster analysis (CA), it was found that the best time and temperature for LTC in kiwifruit was 7 days and 4 ℃, respectively. Conclusion: These results indicated that LTC can maintain a higher soluble sugar content by regulating the activity of sugar metabolism-related enzymes during ripening, and kiwifruit has higher nutritional value.