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 lcaves decreased more rapidly than that in inner lcaves during storage．In outer leaves there were marked chan ges in

supemxide dismutase(SOD)and catalase(CAT)activities and the activities of the two enzymes decreased rapidly after 4 days of storage with a mole obvious decrease in CAT activity．Pemxidase(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 pemxidation．In inner lcaves 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 iBrier lcaves prevented the accumulation in activated oxygen and the progress of me mb rane lipid pemxidation. It could be concluded that the senescence of B.chinensis var．commumis 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.

Brassica campestris L. ssp. chinensis (L.) Makino．var. communis, Activated oxygen, Lipid peroxidation, Postharvest physiology, Senescence

CLC Number: 

• S 634.3