【摘要】 扁蕾(Gentianopsisbarbata)具有鲜艳的花和显著的腺体,并且花开放的前5d柱头和花药始终处于不同的位置(雌雄异位),这些花综合征表明该植物应为异花传粉。为检验这一假设,我们对青藏高原植物扁蕾的海北站种群进行了3年的传粉生物学研究实验。与花综合征所表明的繁育系统相反,两年的野外观察发现昆虫的访花频率十分低,不去雄并隔离昆虫处理也能产生大量种子,说明这一种群的繁殖主要是依赖于自花传粉。尽管利用种子结实评价的柱头可授性从花开放4d后开始下降,但随着花的发育进程,雄蕊的伸长能使得花药与柱头完全接触。实验也证明,柱头可授性和花粉活力都超过5d,说明花药和柱头的接触能够发生自花授粉。扁蕾的这种自花传粉机制应属于典型的延迟自交类型。自花授粉发生在单花花期快要结束前,自交之前仍然保持异交传粉机制,这种延迟自交避免了自交与异交竞争造成的花粉或者种子折损,并为扁蕾在青藏高原极端环境下由于访花昆虫缺乏造成的异交失败提供了繁殖保障。更多还原

【Abstract】 Aims Gentianopsis barbata displays showy flowers and conspicuous nectaries and has stigma and anthers at different positions (herkogamy) until the fifth day after flower opening. All of these floral syndromes were assumed to favor outcrossing. Methods We studied pollination biology of this species at Haibei Station on the Qinghai-Tibetan Plateau for three years to test this assumption. Important findings Contrary to expectation, reproduction in the studied population was mainly through self-pollination. Pollinator visitation was rare, and bagged flowers with anthers set abundant seeds. Both stigma receptivity and pollen viability extended beyond five days. Although stigma receptivity based on seed number decreased after the fourth flowering day, contact of anthers and stigma during floral development resulted in delayed selfing in this species. This delayed selfing retained the floral syndromes and mechanisms for outcrossing, avoided competition between selfing and outcrossing and insured reproduction of G. barbata despite lack of pollinators in arid habitats of the Qinghai-Tibetan Plateau.更多还原