Abstract: Endogenous hormones IAA, ZR, GA₃ and ABA in methanol extract of Rosa rugosa C.V Plena leaf during flower bud differentiation were isolated and purified, and their contents were determined. The results showed that during flower bud differentiation, IAA and GA₃ contents decreased gradually, with the minimum when flower bud begun to differentiate, while ZR and ABA were quite the contrary. The ratios ABA/GA₃, ABA/IAA, ZR/GA₃, and ZA/IAA had an increasing trend, with a leap, suggesting that they played an important role in regulating the process of Rosa rugosa C.V Plena flower bud differentiation. It’s speculated that increasing the ABA and ZA contents or decreasing the IAA and GA₃ contents in Rosa rugosa C.V Plena might be able to accelerate its flower bud differentiation.

Key words: Rosa rugosa C.V Plena, flower bud differentiation, endogenous hormone