Abstract: The relationship between fruit quality and active oxygen species metabolism near the epidermis and core of nectarine during postharvest ripening and pathogensis caused by artificial infection with Monilinia fructicola was analyzed. The results indicated that membrane integrity and peroxidase (POD) activities declined, juice rate, lipoxygenase (LOX) activities and H2O2 content increased, while the activities of catalase (CAT), ascorbate peroxidase (APX) and polyphenol oxidase(PPO) increased firstly and then decreased during postharvest ripening and pathogenesis. Partial least squares regression (PLSR) results identified that membrane integrity was significantly negatively correlated with juice rate, H2O2 content or LOX activity but significantly positively correlated with POD activity or APX activity. Pathway coefficient analysis results showed that the activities of APX, POD, LOX and PPO had a negative effect on the content of H2O2, and the order of the effects was APX＞POD＞LOX.

Key words: nectarine, senescence, diseases, principal component analysis, partial least squares regression, path coefficient analysis