Abstract: Mosia hangchouensis Matsuda is an endangered species distributed along the coastal areas of Zhe-jiang Province. We studied the pollination intensity, pollinators' efficiency and nutlet set in a natural population in Hangzhou and an artificial population in Beijing Experimental Garden of our Institute to test the hypothesis that nutlet set is dependent on pollination intensity and pollinators' efficiency. Although this species is self- compat-ible, careful examination on stigmas of virgin flowers revealed that no stigma was pollinated before corolla open-ing due to the spatial isolation between stigmas and anthers. This indicated that nutlet set is dependent on polli-nators. Hand pollination experiment in the natural population showed close nutlet set between self- pollination, geitonogamy and cross - pollination. Significant effect of pollination intensity on nutlet set was found by the anal-ysis of variance of nutlet set( F = 71.606 * * * , P < 0.01).

Key words: Mosla hangchouensis, Nutlet set, Pollination

摘要： 杭州石荠苎（Mosla hangchouensis Matsuda）自交亲和，人工自花授粉、同株异花授粉和异花授粉的结实没有明显差别。杭州自然居群中新开花朵的调查没有发现闭花传粉现象，原因是花药和柱头之间存在空间隔离和发育上的时间隔离。这些隔离使昆虫成为花粉传播的必要媒介，结实从而取决于传粉昆虫的活动。对比研究发现，传粉对结实有极显著的影响 （F=71.606），而花朵在花序中的位置对结实不存在显著的影响。杭州石荠苎自然居群的传粉强度小于北京实验居群，结实率也显著低于北京实验居群。在杭州自然居群中，早花植株的传粉强度小于正常花期植株的传粉强度，在结实上也有极显著差别。自然居群和实验居群除传粉强度不同外，传粉昆虫的传粉效率也有明显的差别。实验居群的传粉昆虫是效率高的蜜蜂，其个体数量占有绝对优势；而自然居群高传粉效率的昆虫非常少见，主要传粉昆虫是效率较低的淡脉隧蜂，且不到访花昆虫的一半。作者认为，杭州石荠苎的结实受传粉强度和传粉昆虫的传粉效率的限制。针对与结实有关的传粉效率问题，作者提出“有效传粉”的概念，即在柱头的可接受期内有足够多的有活力的花粉到达柱头才能保证结实达到最大。

关键词: 杭州石荠苎, 传粉, 结实