白菜采后衰老生理的研究

Studies on Postharvest Senescence Physiology of Brassica campestris L.ssp. chinensis(L.)Makino.

‘早油冬’白菜采后在 (2 0± 1)℃、 85 %～ 95 %相对湿度条件下贮藏时 ,乙烯释放量呈下降趋势 ,失重率迅速升高 ,呼吸速率先下降后上升 ,于第 6天形成呼吸高峰。外叶叶绿素、可溶性蛋白质和类胡萝卜素含量下降比内叶快。外叶贮藏中SOD和CAT活性变化较大 ,4d后迅速下降 ,特别是CAT活性降幅更大 ;POD活性先逐渐增加 ,6d后急剧上升 ,MDA含量先缓慢增加 ,4d后急剧上升 ,表明活性氧代谢失调 ,膜脂过氧化加剧。内叶SOD和CAT变化很小 ,并保持较高水平 ,POD活性无显著上升 ,MDA略呈下降趋势 ,表明活性氧的产生与清除相平衡 ,从而防止了活性氧积累和膜脂过氧化加强。结论 :白菜的衰老是活性氧代谢失调的结果 ,外叶比内叶容易衰老。

The ethylene production of'Zaoyoudong'Chinese cabbage〔Brassica campestris L.ssp.chinensis(L.)Makino.var.communis〕tended to decline,the weight-loss increased rapidly,and respiration rate showed a climacteric-like pattern with climacteric on 6th day in the duration of storage under the conditions of(20±1)℃,85%-95% relative humidity.The content of chlorophyll,soluble proteins and carotenoid in outer leaves decreased more rapidly than that in inner leaves during storage.In outer leaves there were marked changes in superoxide dismutase(SOD)and catalase(CAT)activities and the activities of the two enzymes decreased rapidly after 4 days of storage with a more obvious decrease in CAT activity.Peroxidase(POD)activity and malondialdehyde(MDA)content increased gradually and then rose sharply after 6 days and 4 days of storage,respectively,indicating an inbalanced metabolism of activated oxygen occurred and resultant accumulation in activated oxygen was associated with membrane lipid peroxidation.In inner leaves the activities of both SOD and CAT were at high level and varied very little while POD activity didn't increased significantly,but MDA concentration declined a little.These data indicated a balance between the production and elimination of activated oxygen existed in inner leaves prevented the accumulation in activated oxygen and the progress of membrane lipid peroxidation.It could be concluded that the senescence of B.chinensis var.communis was caused by maladjusted metabolism of activated oxygen with outer leaves being senesced much easier than inner leaves,therefore,the key factor for storage of Chinese cabbage is to delay the senescence in outer leaves.