关键词: 桂花, 花芽分化, 聚伞花序, 圆锥花序, 成花机制

Abstract: 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 Osmanthus fragrans‘Sijigui’have two different flowering mechanisms.

Key words: Osmanthus fragrans, flower bud differentiation, cyme, panicle, flowering mechanism