3种雌雄异熟樟科植物开花动态的比较研究

Comparison Study of Flowering Process in Three Dichogamous Lauraceae Species

关键词:  阴香  紫楠  浙江楠  雌雄异熟  开花  蜜腺  退化雄蕊

Key words:  Cinnamomum burmannii  Phoebe sheareri  P. chekiangensis  Dichogamy  Flowering  Nectary  Staminode

摘要:  为了解樟科植物雌雄异熟的繁育系统特点，对3种樟科植物阴香（Cinnamomum burmannii）、紫楠（Phoebe sheareri）和浙江楠（Phoebe chekiangensis）雌雄异熟花的开花动态进行了比较研究。结果表明，3种植物雌性功能期的开始时间、雌性功能期和雄性功能期的时间分配有差异。3种植物的主要传粉者均为中华蜜蜂，在雌性功能期和雄性功能期均有访花；在雌性功能期第四轮退化雄蕊蜜腺和雄性功能期第三轮花丝基部的蜜腺分泌花蜜，不同开花阶段的花蜜蜜量和含糖量没有显著差异；柱头可授性和花粉活力在雌性和雄性功能期均较高；雌性功能期和雄性功能期均有自然花粉落置；座果率均是异交补粉 > 自然 > 套袋，表明都存在一定的传粉限制。因此，樟科植物雌、雄性阶段时间分配的不同，可能与退化雄蕊蜜腺和第三轮雄蕊附属蜜腺的分泌节律有关。

Abstract:  In order to understand the characteristics of breeding system of dichogamous Lauraceae plants, the flowering dynamics of hermaphrodite of Cinnamomum burmannii, Phoebe sheareri and P. chekiangensis were compared. The phases of floral phenology and insect pollinators were observed. Stigma and pollen viability, nectar volume, nectar sugar concentration and natural pollen deposition were measured. Fruit setting were checked with different methods. The results showed that the start time and duration of female and male functional stages were different among three species. Apis cerana was the main pollinator at both of female and male functional stages. The nectary in the 4^th round staminodia at female functional stage secreted nectar, while that in the 3^rd round of filament base secreted nectar in male functional stage. Nectar volume and nectar sugar concentration had no significant difference at different flowering stages. Stigma receptivity and pollen viability were higher in both male and female functional stages, there was natural pollen deposition during the whole flowering stages. Fruit setting of three species was in the order of outcrossing and pollination>natural pollination>bagging, indicating that there were certain pollination restrictions. Therefore, it was suggested that the difference of time distribution between male and female stages in Lauraceae might be related to the secretion rhythm of nectary in staminodia and the third round stamen.