Abstract: A field experiment was conducted to study the effects of ripeners Diguat and Roundup on the chlorophyll content, activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), cell membrane permeability, and malondialdehyde (MDA) content of rapeseed pods. Under effects of Diquat, the chlorophyll content decreased, while the activities of SOD, POD, and CAT, cell membrane permeability, and MDA content increased significantly, leading to the peroxidation of membrane lipid. These effects increased with increasing Diquat concentration. After treated with Roundup, the chlorophyll content had less change, activities of SOD, POD, and CAT increased slowly, and cell membrane permeability and MDA content had no obvious increase. With the increasing time of ripeners treatment, the activities of protective enzymes were inhibited to different degree, possibly due to the changes of molecular structure of antioxidant enzyme system under effects of the ripeners.

Key words: rapeseed pod, chemical ripener, chlorophyll content, cell membrane permeability, MDA, protective enzyme, Wanning Reservoir, entropy weigh, ecosystem health assessment, ecosystem health comprehensive index, trophic state index, principal component analysis.