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| Effect of Exogenous Gibberellin on the Contents of Endogenous Hormones in Stem Apex of Broccoli |
| Wang Tingqin，Yang Xian |
| Agriculture College，Guangdong Ocean University，Zhanjiang 524088 |
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Abstract Different concentrations of exogenous gibberellin（GA）（50 mg•L-1，100 mg•L-1，150 mg•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.
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Received: 11 December 2007
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