珍稀濒危植物细果秤锤树开花生物学特性和繁育系统

为了解珍稀濒危植物细果秤锤树（Sinojackia microcarpa）开花特征和有性繁殖，对其花部形态特征、开花动态、花粉胚珠比（P/O）、柱头可授性、花粉活力、套袋试验、访花昆虫及访花频率进行观测。结果表明：（1）细果秤锤树的杂交指数（OCI）为4，单花期5~7 d，种群花期可持续20 d左右。花粉与胚珠比为4 093.21±498.56。开花后第3天的花粉活力最高（76.21%），而开花后第7天时花粉活力较低（18.37%）。细果秤锤树柱头最适可授期在开花后第2天。（2）套袋试验表明，细果秤锤树存在部分自交不亲和性，同时不存在无融合生殖，传粉昆虫是其完成生殖过程所必需的，且异株授粉能够提高其坐果率和结籽率。细果秤锤树的访花昆虫有3目5科7种，主要访花昆虫有黄胸木蜂（Xylocopa appendiculata）、熊蜂（Bombus sp.）、胡蜂（Vespa sp.）、中华蜜蜂（Apis cerana）、黑带食蚜蝇（Episyrphus balteatus）、其中熊蜂平均访花频率最高，达（8.67±0.21） 次·h^-1。对该物种开花生物学特征与繁育系统进行深入研究，有利于进一步探究其濒危机制，为后续珍稀濒危植物的研究提供理论依据和参考。

Flowering Biological Characteristics and Breeding System of the Rare and Endangered Plant of Sinojackia microcarpa

In order to illustrate the flowering characteristics and sexual reproduction of the rare and endangered plant Sinojackia microcarpa， the morphological characteristics of flower， flowering dynamics， pollen ovule ratio（P/O）， stigma receptivity， pollen viability， bagging experiment， pollinator insects and pollinator frequency were investigated respectively. The results showed that： （1）the hybridization index（OCI） was four， the flowering period was 5-7 d， and the flowering period of the population lasted 20 d. Pollen to ovule ratio was 4 093.21±498.56. The pollen viability was the highest on the third day after flowering（76.21%）， but the lowest on the seventh day after flowering（18.37%）. The most suitable period of stigmas was on the second day after flowering. （2）The bagging result showed that： there were some self-incompatibility and no apomictic reproduction in S. microcarpa. Pollinators were necessary for the reproductive process of S. microcarpa， and cross-pollination could improve the rate of fruit and seed setting. There were seven species， five families and three orders in the visiting insects of S. microcarpa. The main pollinators were Xylocopa appendiculata， Bombus sp.，Vespa sp.，Apis cerana，Episyrphus balteatus. The average pollinator frequency of Bombus sp. was （8.67±0.21） times per hour. Further research on the biological characteristics of flowering and breeding system of this species would be helpful to further explore the mechanism of its endangerment， and provided theoretical basis and reference for future studies on rare and endangered plants.