油菜素内酯对青花菜茎尖核酸和激素含量的影响

Effects of Brassinolide on Contents of Nucleic Acid and Endogenous Hormones in Stem Apex of Broccoli

用0.001、0.01和0.1mg.L-1油菜素内酯(BL)在青花菜花芽分化前20d和分化后10d分别进行叶面喷施处理,研究其对青花菜花芽分化期和现蕾期茎尖核酸和内源激素含量的影响。结果表明:0.001和0.01mg.L-1BL处理可促进茎尖RNA和总核酸的合成。BL处理促进花芽分化期DNA的合成,但抑制现蕾期DNA的合成。BL明显影响青花菜茎尖内源激素的平衡,显著抑制IAA的合成,降低花芽分化期和现蕾期茎尖IAA含量,提高花芽分化期茎尖内源GA1/3和iPAs的含量,但现蕾期茎尖内源GA1/3和iPAs含量却降低。结果显示,植株体内内源激素在不同生育期对外源BL的响应有所不同。

Different concentrations of brassinolide （ BL, 0. 001,0.01 and 0. 1 mg· L^-1 ） were sprayed on leaves of broccoli at 20＇h day before or 10＇h day 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 in treatments at 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 GA1/3 and iPAs in stem apex obviously increased in BL treatments during the period of inflorescence differentiation, but the contents of endogenous GA1/3 and iPAs in stem apex decreased during the period of curd emergence. Different responses of endogenous hormones in plant to exogenous BL were observed in this experiment.