‘四季桂’不同季节的花芽分化与发育比较

利用显微解剖和石蜡切片技术,对四季桂品种群中‘四季桂’(Osmanthus fragrans‘Sijigui’)不同季节的花芽分化及开花特性进行研究。‘四季桂’一年成花3次,分别于3月初、6月上旬和10月底开始花芽分化,4月下旬、8月底和11月底完成,分别历时约2个月、2个半月和1个月。6月开始的花芽分化和开花过程与秋桂品种群基本相似,分化后需要低温才能开花,最终形成聚伞花序,无总梗,花粉发育正常。而10月底分化的花芽在完成分化后随即开花,形成的花序有总梗,且有伸长与未伸长之分,长度分别为(0.80±0.11)cm和(3.50±0.71)cm。3月分化的花芽与新梢同时生长发育,分化完成后随即开花。春季和冬季的两次分化形成的均是圆锥状花序,具总梗,花粉均败育。结果表明‘四季桂’自身存在着不同的成花机制。

Comparison on Flower Bud Differentiation and Development of Different Seasons in Osmanthus fragrans ‘Sijigui’

The micro-dissection technique and paraffin method were used to study flower bud differentiation and flowering characteristics of different seasons in Osmanthus fragrans ‘Sijigui’ ‘Sijigui’ flowered 3 times every year,whose flower bud differentiations respectively beginning in early March,early June and late October and ending in late April,late august and late November,and lasting for about 2 months,2 and a half months and one month.The flower bud differentiation and flowering process that began from June were similar to autumn-flowering cultivars which flowered only one time in autumn every year.Analogously,the flowers in this season would open only experiencing sufficient cooling capacity after completion of flower bud differentiation and finally formed cyme which had no inflorescence stalks and whose flowers had normally developed pollen.The flower buds that initiated in October immediately developed into panicle with inflorescence stalks,whose flowers opened continuously.The inflorescence stalks were divided into short stalks and long stalks,whose lengths were (0.80 ± 0.11) cm and (3.50 ± 0.71) cm respectively.The flower buds that initiated in March developed synchronously with new shoots into panicle,and the flowers opened continuously after the completion of differentiation.The results show that Osmanthusfragrans ‘Sijigui’ have two different flowering mechanisms.