外源赤霉素对青花菜茎尖内源激素含量的影响

以不同浓度赤霉素（GA）分别在青花菜花芽分化前20 d（播后40 d）和花芽分化后10 d（播后70 d）叶面各喷施1次，研究外源GA对青花菜茎尖内源激素含量的影响。结果表明，青花菜生长发育过程与植株内源激素含量变化密切相关，在花芽分化期茎尖IAA、GA1/3含量保持较低的水平和适宜的iPAs含量有利于花芽分化，而在现蕾期保持适宜水平的IAA、GA1/3含量及较低水平的iPAs含量则有利于花球的形成。外源GA明显地影响了青花菜茎尖内源激素的平衡，GA处理在花芽分化期和现蕾期均抑制了茎尖IAA合成，降低了茎尖IAA含量；较低浓度的GA处理在花芽分化期可增加茎尖GA1/3含量，浓度升高反而降低其含量，但在现蕾期正好相反；GA处理在花芽分化期促进了iPAs含量的升高，而且浓度越高iPAs含量也越高，但在现蕾期低浓度GA处理可提高茎尖iPAs含量，而浓度过高反而导致iPAs含量下降。

Effect of Exogenous Gibberellin on the Contents of Endogenous Hormones in Stem Apex of Broccoli

Different concentrations of exogenous gibberellin（GA）（50 mg&;#8226;L-1，100 mg&;#8226;L-1，150 mg&;#8226;L-1）were sprayed on leaves of broccoli at the 20th day before and 10th day after inflorescence differentiation，respectively.The effect of exogenous gibberellin on the contents of endogenous hormones in stem apex of broccoli was studied.The results indicated that the development of broccoli was closely correlated with changes of endogenous hormones in plant.It was favorable for flower differentiation at inflorescence differentiation period to keep lower contents of IAA，GA1/3，and proper level of iPAs in stem apex，whereas proper levels of IAA，GA1/3，and keep lower content of iPAs was in favor of curd formation at curd emergence period.The balance of endogenous hormones was influenced by exogenous GA in stem apex of broccoli.The synthesis of IAA was inhibited by exogenous GA in stem apex，so its content decreased at both periods of inflorescence differentiation and curd emergence.The content of GA1/3 in vivo increased under treatment of low concentration of exogenous GA，but decreased under treatment of high concentration of exogenous GA.However，the changes of GA1/3 content in vivo exhibited the contrary tendency at curd emergence period.The content of iPAs increased with increment of the treated concentrations of GA at the stage of inflorescence differentiation.On the contrary，iPAs content decreased with increment of treated concentrations of GA at the stage of curd emergence.