Abstract: Changes of the activities of protective enzymes and superoxidation of membrane lipid in leaves during unfolding and contabescence were studied using the muskmelon varieties of Honey World and Yilishabai grown in solar greenhouse by mensurating the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of malondialdehyde (MDA). The results indicated that the SOD activity increased continuously during 7～21 d of leaf age and decreased at short notice; and the SOD activity of Yilishabai increased rapidly during 28～35 d while it increased until 42 d for Honey World. Subsequently, it declined sharply. The activities of POD and CAT, and the content of MDA all increased at first but declined whereafter. The activities of CAT rised from 7 d to 21 d and 28 d of leaf age for Yilishabai and Honey World, respectively, and declined continuously whereafter. The activities of POD rised from 7 d to 49 d and 56 d of leaf age for the two varieties, respectively, and declined sharply subsequently. The change of MDA content was similar to the POD activity. The activities of SOD and CAT for the serotinous muskmelon cultivars were remarkablely higher than those of premature cultivars while the POD activity and MDA content were lower obviously during senescence of leaves.

Key words: Muskmelon, Leaf unfolding, Leaf senescence, Activities of protective enzymes, Superoxidation of membrane lipid

CLC Number: 

• S652.01