Abstract: The effects of bagging on the sink strength of Fuji apple fruit was studied in the same source-sink units established by girdling（the ratio of leaf number to a fruit was 40︰1）. The accumulation and metabolism of fruit carbohydrates were measured after bagging. The results showed that more sorbitol was accumulated in fruits 45 d after bagging than nonbagged fruits（control），but less starch，glucose，fructose and sucrose in bagged fruits. The activity of enzymes related to sugar metabolism such as sucrose synthase（SS），sucrose phosphate synthase（SPS），acid invertase（AI），sorbitol dehydrogenase（SDH）and amylase of bagged fruits was corresponded to decrease. The results indicated that metabolism of carbohydrates was inhibited in bagged fruits. It is suggested that sink vitality of fruits was declined by bagging.

Key words: apple, bagging, sorbitol, sucrose, carbohydrates metabolism