Abstract:

In the present study, the effects of different temperatures (15 ℃ or 5 ℃), waxing and mechanical damage on the changes in the activities of peroxide (POD), polyphenol oxidases(PPO), and phenylalanine ammonia-lyase (PAL) as well as the incidence of peel pitting in “Fengjie” navel orange (Citrus sinensis Osbeck) fruits. The results showed that the incidence of peel pitting is greatly enhanced by waxing and mechanical damage, which indicates that waxing and mechanical damage may be the important factors inducing peel pitting, while the low temperature (5 ℃) can decrease the incidence of this disease. Moreover, mechanical damage distinctly stimulates the increase of the activities of POD and PAL, and the PPO activity is promoted by both of waxing and mechanical damage, while the 5 ℃ storage treatment inhibits the PPO activity. It is suggested that the enzyme activities of POD, PPO and PAL are highly related to peel pitting occurred on “Fengjie” navel orange fruits.

Key words: navel orange (Citrus sinensis Osbeck), peel pitting, POD, PPO, PAL