关键词: 青花菜, 油菜素内酯, 核酸, 内源激素

Abstract: Different concentrations of brossinolide(BL) (0.001, 0.01 and 0.1mg·L^-1) were sprayed on leaves of broccoli at 20 th days before or 10 th days after inflorescence differentiation, respectively. Effects of brassinolide on contents of nucleic acid and endogenous hormones in stem apex of broccoli was investigated during the periods of inflorescence differentiation and curd emergence. Results showed that the synthesis of total nucleic acid and RNA could be improved under treatment of both concentrations of 0.001 and 0.01 mg·L^-1 BL. The synthesis of DNA was enhanced by BL at inflorescence differentiation period, whereas was inhibited at curd emergence period. The balance of endogenous hormones in stem apex was obviously influenced by BL. The synthesis of IAA in stem apex was depressed by BL, so the content of IAA decreased at both stages of inflorescence differentiation and curd emergence. The contents of GA_1/3 and iPAs in stem apex obviously increased under BL treatments during the period of inflorescence differentiation, but the contents of endogenous GA_1/3 and iPAs in stem apex decreased durng the period of curd emergence. Different responses of endogenous hormones in plant to exogenous BL were observed in this experiment.

Key words: broccoli, brassinolide, nucleic acid, endogenous hormones