Abstract: Changes in reactive oxygen species (ROS) metabolism-related physiological indexes were studied during the postripeness and senescence of ‘Golden Delicious’ and ‘Fuji’ apples stored at (23 ± 2) ℃. The results showed that the firmness of ‘Golden Delicious’ apples decreased faster than that of ‘Fuji’ apples and the respiration and ethylene peaks occurred 49 days earlier in ‘Golden Delicious’ apples than in ‘Fuji’ apples. The rate of superoxide anion radical (O2-·) production and the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in ‘Golden Delicious’ apples were higher than those in ‘Fuji’ apples during storage. The activities of peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) in ‘Fuji’ apples were lower than those in ‘Golden Delicious’ apples during the whole storage period (P < 0.05, P < 0.01), and their peak activities occurred 63, 56 and 49 days later than in ‘Golden Delicious’ apples, respectively. Although glutathione reductase (GR) activity reached its peak in ‘Fuji’ apples 49 days later than in ‘Golden Delicious’ apples, its peak value was 2.11 times higher than that in ‘Golden Delicious’. Moreover, compared with ‘Golden Delicious’ apples, ‘Fuji’ apples maintained higher ascorbic acid (AsA) content and lower ascorbate peroxidase (APX) activity during postharvest ripening. In conclusion, the ROS level and ROS metabolism-related enzyme activities in ‘Golden Delicious’ apples were higher than those in ‘Fuji’ apples, and the ripening and senescence rate was faster than that in ‘Fuji’ apples after harvest. Thus, the storage life of ‘Golden Delicious’ apples was shorter than that of ‘Fuji’ apples. These data indicate that the storability of different apple cultivars may be closely related to ROS level, but considering the complex ROS production and scavenging system, its relationship with ROS metabolic capacity still needs to be further elucidated.

Key words: apple; postripeness; reactive oxygen species metabolism; senescence