Abstract: This paper deals with the effects of PP333 and GA on bud formation of Longan and rela- tion to endogenous hormones. Results showed that the content of ipA in buds of Longan treated with PP333 was obviously higher than that treated with GA, while the content of GA was gradually decreased from high to low. The both contents treated with GA were contrary. The content of ABA in buds treated with PP333 was lower than that treated with GA. It indicated that high contents of GA and ABA were disadvantageous to bud differentiation and high content of cytokinin(ipA) in buds was advantageous to bud differentiation. Spraying of PP333 could shorten the longth of inflorescence and increase the fruit set and yield.

Key words: Dimocarpus longana