白玉兰二次开花诱导与生理调控研究

Induction and physiological regulatory mechanism of secondary flowering in Yulannia denudata

【目的】通过人工诱导实现白玉兰(Yulania denudata)二次开花,以探明白玉兰花芽分化与开花诱导的生理调控机制。【方法】采用施用营养肥与激素处理白玉兰植株,进行花芽发育石蜡切片观察,并测定不同时期花芽内源激素含量。【结果】5月上旬随着营养生长趋于减缓,白玉兰起始花芽分化,至6月上旬花芽分化基本完成;单独采用外源激素(6-BA、GA_(3))或配合施用营养肥(N、P、K、糖),可诱导白玉兰当年二次开花,二次开花株率33%~100%,单株最大开花量22;花芽分化成熟过程中,内源GA_(3)与ABA含量升高,而打破休眠、开花的花芽内脱落酸(ABA)含量下降,内源生长素类激素(IAA、ME-IAA)含量升高;较未开花对照,外源细胞分裂素处理株花芽内ME-IAA、IPA、JA-Ile、JA含量较高,外源赤霉素(GA_(3))处理株内源tZR、GA_(1)、GA_(3)含量较高。【结论】外源激素可不依赖于营养处理直接诱导白玉兰二次开花,不同激素诱导白玉兰二次开花可能存在不同的开花调控通路。

【Objective】The aim of this study was to achieve the secondary flowering of Yulannia denudata through artificial induction and to explore the physiological regulation mechanism of flower bud differentiation and flowering induction in Y.denudata.【Method】Y.denudata plants were treated with nutrients and hormones.Flower buds were embedded in paraffin and sectioned to observe flower bud development,and endogenous hormone contents in flower buds at different stages were measured.【Result】Flower bud differentiation of Y.denudata began in early May when vegetative growth slowed down and was completed by early June.Secondary flowering within the same year was induced via treatment with exogenous hormones[6-benzylaminopurine(6-BA)and gibberellin A_(3)(GA_(3))]alone or in combination with nutrient applications[nitrogen(N),phosphorus(P),potassium(K)and sugars].The secondary flowering rate ranged from 33%to 100%,with the maximum of 22 flowers per plant.During the maturation of flower bud differentiation,the levels of endogenous GA_(3) and abscisic acid(ABA)increased.The ABA content in flower buds decreased while breaking dormancy and flowering,whereas the content of endogenous auxins(indole-3-acetic acid(IAA)and methylindole-3-acetic acid(ME-IAA))increased.Flower buds treated with exogenous cytokinins had higher levels of ME-IAA,IPA,jasmonoyl-l-isoleucine(JA-Ile)and jasmonate(JA),while flower buds treated with exogenous gibberellins(GA_(3))had higher levels of endogenous trans-zeatin riboside(tZR),gibberellin A_(1)(GA_(1)),and GA_(3).【Conclusion】Exogenous hormones directly induce secondary flowering in Y.denudata without relying on nutrient treatments.Thus,different hormones may induce secondary flowering through various regulatory pathways.