蓖麻花序特征及花芽分化的初步研究

摘要

对蓖麻花序特征、顶芽分化及内源IAA和ABA含量变化进行初步研究,结果表明:不同品种(系)间雌花率及雌花密度均存在极显著差异.蓖麻雌花并非完全单性花,各品种(系)雌花均存在退化雄蕊痕迹,但其发生率不同,单雌后代品系明显高于供试品种.单雌花序与两性花序的雌花中均存在退化雄蕊,且无显著差异,但花序中下部与上部之间差异显著.顶芽石蜡切片观察表明:蓖麻在5叶期以前,其顶芽基本处于叶芽生长阶段；在6～9叶期,顶芽逐渐进入花芽分化、生长阶段,顶芽内源IAA、ABA含量变化也十分明显.不同性别花序和花的内源激素含量显示:IAA含量,单雌花序＞雌花＞两性花序＞雄花；ABA含量,雄花显著高于雌花,但两性花序却明显低于单雌花序；IAA/ABA值,雌花＞单雌花序＞两性花序＞雄花；说明IAA含量和IAA/ABA相对含量可能在花性分化中具有较为重要的作用.%Inflorescence characteristics, bud differentiation and changes of endogenous IAA and ABA hor-monecontents of castor bean were studied. The results showed that female flower density and percentage had highly significant difference among twelve tested cultivars (lines). The pistillate flower was not special unisexual floweret, regressive stamens were discovered in the bracts or basis of some female flowers of all materials. The frequency of its occurrence varied among the twelve cultivars (lines). And it was significantly higher in strains from pistillate progenies than in cultivars. Regressive stamens arose in some female flowers of monoecious inflorescences and pistillate racemes, and the emergency ratio showed no significant discrepancy, but showed difference between lower and upper inflorescences. Observation of apical bud differentiation was conducted by the method of paraffine section. It was observed that apical buds were mainly leaf buds before stage of five leaves, but changed to flower buds gradually at stage of six to nine leaves. During these periods, the concentration of endogenous IAA and ABA hormones varied. The content of endogenous IAA and ABA for different sexual raceme and flower were compared. IAA content was shown as pistillate inflorescence > female flower > monoecious inflorescence > male flower. ABA concentration was higher in male flower than in female flower,and lower in monoecious raceme than in pistillate inflorescence. IAA/ABA was as follows: female flower > pistillate inflorescence > monoecious inflorescence > male flower. It suggested that IAA concentration and IAA/ABA value had an important role in flower sexual differentiation in castor bean.