Abstract: The effects of spraying the different concentration and combination of gibberellin acid (GA₃) with indol-3-yl acetic acid (IAA) on the correlated enzyme activities in the lignin biosynthesis of Neosinocalamus affinis and their relationships with the lignin content and S/G were studied. It aims to provide the theoretical evidence for the quality cultivation and genetic improvement. The results showed that the treatment of GA-350IAA200 increased the enzyme activities of 4CL, but the GA-3200IAA50 repressed the enzyme activities of 4CL about 50 days after spraying GA₃ and IAA, and changed the tends of dynamic changes of 4CL enzyme activities compared with the control. The GA₃ and IAA could improve the CAD enzyme activities and significantly repress the PAL enzyme activities. After spraying the different concentration and combination of GA₃ with IAA, the correlated analysis results showed that the negative relationships of the 4CL enzyme activities with the lignin content and S/G value were found, the positive relationships of the PAL enzyme activities with the lignin content was not significant, the positive or negative relationships of the CAD enzyme activities with the lignin content and S/G value were not significant. The correlated enzyme activities in the lignin biosynthesis were regulated by spraying the different concentration and combination of GA₃ with IAA, but the effects of GA₃ and IAA on the correlated enzyme activities were related to their concentration and combination.

Key words: Neosinocalamus affinis, Lignin, Enzyme Activities, IAA, GA₃