Effects of 1-Methylcyclopropene Treatment on Postharvest Quality and Metabolism of Different Kiwifruit Varieties

The kiwifruit (Actinidia) is an important nutritional and economic fruit crop. However, the short edible window period of kiwifruit has seriously affected its market value. 1-Methylcyclopropene (1-MCP), as a novel ethylene inhibitor, is widely applied to delay fruit ripening and senescence. To our knowledge, there are limited studies on the effects of 1-MCP on fruit quality and metabolism of different kiwifruit varieties. Three kiwifruit cultivars (i.e., 'Xuxiang', 'Huayou', and 'Hayward') widely cultivated in China were chosen as our research objects. The variations of storage quality and metabolic characteristics of kiwifruits treated with various 1-MCP concentration (0 μL/L, 0.5 μL/L, and 1.0 μL/L) were systematically investigated. The results showed that 1-MCP treatment significantly improved the quality of kiwifruit during storage. Among them, for 'Xuxiang' and 'Hayward' varieties, 1.0 μL/L 1-MCP treatment could delay the decrease in fruit firmness, the increase in maturity index and cellulase activity, and inhibit the decrease in ascorbic acid (AsA) level. However, the 0.5 μL/L 1-MCP had a great influence on the chlorophyll content and maturity index of the 'Huayou' cultivar, and the preservation effect was satisfactory. In addition, gas chromatography-mass spectrometry (GC-MS) based metabolomics studies revealed that 1-MCP treatment affected carbohydrates metabolism, fatty acids metabolism, and amino acids metabolism in different kiwifruit varieties. Correlation analysis indicated that sugars metabolism has the closest relationship with postharvest physiological quality. This research indicated that the effectiveness of 1-MCP treatments was dependent on fruit variety and treatment concentration. Furthermore, these findings provide a theoretical foundation for extending the shelf life of different kiwifruit varieties.