厚皮甜瓜叶片展开至衰亡过程中保护酶活性及膜脂过氧化的变化

Changes of the Activities of Protective Enzymes and Superoxidation of Membrane Lipid in Muskmelon Leaves During Unfolding and Contabescence

以目光温室栽培的伊丽莎自和蜜世界厚皮甜瓜为试材，通过测定不同叶龄叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量，探讨了在叶片展开至衰亡过程中保护酶活性和膜脂过氧化变化。结果表明，在叶龄7～21d，SOD活性不断升高，之后短时下降，在叶龄28～35d（伊丽莎自；蜜世界延续到42d），酶活性迅速升高，随后急剧下降。POD，CAT活性和MDA含量均呈“先升后降”的变化趋势：伊丽莎自、蜜世界CAT活性上升分别从7d叶龄持续到21d和28d，之后不断降低；而POD活性上升则分别持续到49d和56d叶龄，随后大幅下降；MDA含量与POD活性变化基本一致。在叶片衰老期间，中晚熟品种SOD和CAT活性显著高于早熟品种，而POD活性和MDA含量则明显偏低。

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.