Abstract: An early sign of chilling injury (CI) of Hami Melon (Cucumis melo L.) was observed as some irregular tiny spots on the rind. As the chilling prolonged (0–2℃), they produced water-soaking lesions and commonly followed by Alternaria rot. The changes of injured tissue were studied using light, transmission electron and scanning electron microscopy. At chilling tempeeature (0–2℃), parenchyma cells under epidermis became firstly flattened and plasmolyzed, and later resulted in the formation of depressed area of epidermal tissue. Initial occurrence of C1 symptoms was at the stomata. After prolonged exposure at chilling temperature, the pinsmalemma and tonoplasts of the parenchyma ceils were destroyed and plasmodesmas also disappeared. Comparing with change of various organelles, the chloroplasts were more sensitive than the mitochondria at chilling temperature, chloroplasts were broken completely during the last period of CI, but mitochondria still kept their structure.

Key words: Hami Melon (Cucumis melo L.), Chilling injury, Subcellular structure, Alternaria rot