侧穗凤仙花的传粉生态和繁育系统

Pollination ecology and breeding system of Impatiens lateristachys(Balsaminaceae)endemic to China

关键词:  凤仙花科  传粉  繁育系统  雌雄异熟  柱头运动  雌雄干扰

Key words:  Balsaminaceae  pollination  breeding system  dichogamy  stigma movement  male-female interference

摘要:

通过对峨眉山特有种侧穗凤仙花的开花生物学特性、花器官结构、传粉者种类和访花行为、繁育系统、花粉胚珠比(P/O)及花粉活力的研究。发现居群之间花的寿命变化比较大,它们的雄蕊期长,雌/雄蕊期比为0.12～0.17; 花粉胚珠比达到4.6万,花粉在开花第一天有很高的活力(>90%); 传粉者为熊蜂和天蛾,熊蜂包括贞洁熊蜂、白背熊蜂; 存在盗蜜者灰熊蜂。侧穗凤仙花是自交亲和的异交植物,能通过雌雄异熟和独特的花部结构来避免自交及雌雄干扰。侧穗凤仙花存在柱头运动现象,并通过柱头运动增强了雌性功能。由于昆虫访花频率很低,侧穗凤仙花自然结果率(26%)很低,人工授粉明显增加了结果率(42%),说明侧穗凤仙花的低结果率可能和传粉者限制有关。

Abstract:

Pollination ecology and the breeding system of Impatiens lateristachys,a species endemic to the Emei Mountain were studied. The floral phenology,floral structure,pollen-ovule ratio(P/O),pollen viability,floral visitors and their behavior,and the breeding system were observed and determined. The flowering phase of the protandrous I.lateristachys lasted for a long time. The life span of an individual changed between the populations,but the female phase-male phase ratio was similar(0.12-0.17). The pollen/ovule ratio was 460 thousand,and pollen viability(MTT test)was at high level on the first day(>90%). The primary pollinators were Bombus festivus Smith and B.parthenius Richards; secondary pollinators were hawk moth; and B.grahami Frison was nectar gatherer. I.lateristachys was a self-compatible species,its special floral structure and protandrous character could avoid selfing and intrafloral male-female interference very well. The stigma movement of I.lateristachys was responsible for enhancing the function of the female. Fruit set was relatively low(26%)under natural conditions,but hand-pollination increased the fruit set(42%). And the pollinator visitation rate(0.2-2.0)was significantly lower than that of other congeneric species(7.1-8.9),indicating that the fruit set may be limited by the shortage of pollinators.