Study On Characteristics Of Fruit Quality And Regulation Of Ripening And Senescence In Post-harvest Cucumis Melo L.’Hetao’ Fruits

’Hetao’melon is Inner Mongolia hetao area of good melon varieties, but post-harvest melon fruits are easy to decay. It has theoretic and practical significance to explore its fruit quality and the regulation of ripening and senescence in post-harvest fruits. In this paper, we use external morphology observation and internal physiological indexes combination methods to explore appearance and nutriment substance, oxygen metabolism, softening mechanism, ethylene content change and the regulation of ripening and senescence in post-harvest fruits stored in natural conditions. The results indicated that:1. In natural conditions, the colour, flavor and character built up after stored2d in post-harvest fruits. After6d, the exterior quality declined, showed rough, thin frangrance, softening and got rot at stored12d.2. In natural conditions, essential nutrient changed in post-harvest fruits. Soluble solid content, soluble protein and organic acid content showed a trend of decline and then rising. Total sugar content kept higher level and declined. Vc continued to rising in storage period.3. In natural conditions, reducing sugar content showed a trend of decline and sucrose showed a trend of rising volatility to the end of the storage. In storage time, starch content showed a trend of rising and then declined. Net activity of regulating sugar enzymes turned from cleavage activity to synthesis activity at2d and reached peaks at4d. Then net activity of enzymes for cleavage activity declined slowly to the end of the storage.4. In natural conditions, the content of active oxygen increased, including O2production rate increased significantly, while H2O2content presented bimodal changes. SOD showed a trend of decline and then rising, however, POD, CAT and APX presented an opposite tendency. They reached peaks at different time and maintained high activity levels for a period and then begun to decline.5. In natural conditions, Relative electrical conductivity and MDA content increased; ethylene appeared unimodal curve changes. At preliminary storage, LOX activity was extremely low, and then rose rapidly and reached peaks. It fell slightly from5d of storage.6. In natural conditions, the hardness of edge and centre were all declined, edge hardness was higher than centre hardness; At preliminary storage, PG activity were extremely low, and then showed a trend of rising volatility from4d to the end of the storage. 7. In storage period, ethylene content appeared unimodal curve change. Ethylene content kept extremely low level at early storage and rose rapidly from6d to10d. The content increased by11times at10days. At this period, fruit quality declined sharply and membrane lipid peroxidation intensified, so ethylene might act as signal molecule start ripening and senescence in post-harvest fruits.