木薯雌雄花分化形态结构观察及生理调控研究

Study on Morphological Structure and Physiological Regulation of Female and Male Flowers Differentiation in Cassava

本研究以木薯品种新选048为试验材料,观察和测定木薯花分化各时期的形态结构、内源激素及碳氮化合物含量,并开展木薯雌雄花分化的外源激素调控研究,揭示木薯花分化规律,初步探究木薯花分化的生理机制。试验结果表明:木薯从花芽分化开始到完成开花的全过程需要30 d,分化出的花序主要有全雄花序和雌少雄多花序两种类型,木薯性别分化前为同时具有雌蕊原基和雄蕊原基的两性花,花序抽出后5~8 d,雌花的雄蕊逐渐退化,花序抽出后5~7 d,雄花的雌蕊逐渐退化消失,形成单性花;在雌雄花分化过程中5种内源激素含量变化存在差异,在不同的分化时期雌花的细胞分裂素(CTK)、乙烯(ETH)含量均高于雄花;在雌雄花分化初期和分化中期雄花中的赤霉素(GA3)含量高于雌花;在分化中期雄花的吲哚乙酸(IAA)含量显著大于雌花;雌雄花的脱落酸(ABA)含量在分化各时期的差异不大;雄花蕾的碳、氮含量均高于雌花蕾,且雄花蕾的碳/氮(C/N)比值也整体高于雌花蕾,特别是在分化初期(5 d)达到了显著差异;外源激素调控雌雄花分化的研究结果表明,不同浓度的6-BA和ETH均有不同程度的促雌作用,其中浓度为60 mg/L的6-BA和1920 mg/L的ETH的效果最佳,而GA3对雄花形态建成具有促进作用,其最佳浓度为40 mg/L。由此可得出结论:木薯雌花分化的关键时期是花序抽出后5~8 d,雄花分化的关键时期是花序抽出后的5~7 d,CTK和ETH对木薯雌花的分化具有促进作用,GA3、IAA和较高的碳/氮比更有利于木薯雄花的分化。

In this study,cassava Xinxuan 048 was used as the material to observe and determine the morphological structure,endogenous hormones and the contents of carbon and nitrogen compounds in different stages of flower differentiation,and to conduct exogenous hormone regulation research to reveal the rules and the physiological mechanism of cassava flower differentiation.Cassava plants complete the whole process from flower bud differentiation to the end of flowering in 30 d,producing mainly two types of inflorescences:staminate and oligopistillate-monoecious.Both pistillate and staminate primordia were present in the same flower bud before sexual differentiation.The stamens gradually degraded in the female flowers 5 to 8 d after elongation of the inflorescence,while pistils gradually degraded and disappeared 5 to 7 d after elongation of the inflorescence,resulting in unisexual flowers.The contents of CTK and ETH were higher in female flowers than in male flowers in all the stages of differentiation,the GA3 content was higher in male flowers than in female flowers in the initial and middle stages of differentiation,the IAA content was significantly higher in male flowers than in female flowers in the middle stage of differentiation,the ABA content in male and female flowers was not of much difference in all the stages of differentiation,the contents of carbon and nitrogen were higher in male flower buds than in female flower buds,and the ratio of C/N was also higher in male flower buds than in female flower buds,especially in the initial stage of differentiation(5 d).The results of the study on the regulation of differentiation of male and female flowers by exogenous hormones showed that different concentrations of 6-BA and ETH had different promoting effects on females.The concentration of 6-BA and ETH at 60 mg/L and 1920 mg/L were the best,while GA3 promoted the formation of male flowers,with the optimal concentration being 40 mg/L.It can be concluded that the key period for female flower differentiation of cassava is 5 to 8 d after inflorescence elongation,and the key period for male flower differentiation is 5 to 7 d after inflorescence elongation.CTK and ETH can promote the female flower differentiation of cassava,and GA3,IAA and higher C/N ratio are more conducive to the male flower differentiation of cassava.