Abstract: Off year trees of ‘Biji’ bayberry were used to determine the effects of GA₃ spraying on lignin level and its correlated enzymes activities in leaves during the period of flower bud physiological differentiation. At the initial stage of flower bud physiological differentiation, the activity of PAL increased to maximum, then followed by the activity of PPO. At the peak of flower bud physiological differentiation, both the activity of POD and the level of lignin increased to maximum. During the period of flower initiation, both the activity of POD and the content of lignin decreased. The treatment with GA₃ spraying inhibited the activities of PAL, PPO and POD, slowed down the biosynthesis of lignin, surppressed the differentiation of flower buds and almost completely prevented the formation of flower bud. We concluded that GA₃ might inhibit the formation of flower bud by dropping down the accumulation of lignin.

Key words: Bayberry (Myrica rubra Bieb. et Zucc), Flower bud physiological differentiation, Lignin, Enzemy activity, Gibberellin₃