长喙毛茛泽泻(泽泻科)的交配系统研究

Studies on Mating System of Ranalisma rostratum (Alismataceae)

对濒危植物长喙毛茛泽泻（ＲａｎａｌｉｓｍａｒｏｓｔｒａｔｕｍＳｔａｐｆ．）的交配系统作了综合研究，结果是：该种的花粉粒和柱头较平滑，花内分泌细胞存在但欠发达，开花前花粉萌发率较高（７１６％）而开花１ｈ后花粉萌发能力急剧衰退，花粉／胚珠比较低（Ｐ／Ｏ＝１０６），花部综合特征与其花前期闭花授粉的交配习性相适应。该种的自然居群及实验居群中均未观察到花间的虫媒传粉，仅有极小型昆虫（蓟马科，Ｔｒｉｐｉｄａｅ）起花内传粉作用，亦未检出风媒花粉流。人工隔离及控制授粉试验显示，该种在人工自交／异交后均有较高结实率，但自然状态下异交机制缺乏。用同工酶遗传标记法得到该种一个实验居群的交配系统特征参数异交率的估计值为ｔ＝０９％。

The mating system of Ranalisma rostratum Stapf., an endangered aquatic species, was studied synthetically. The results are as follows: Pollen grains and stigmas were relatively smooth. Glandular cells occurred in flowers but not well developed. Pollen germination showed a higher level (716%) before flowering and a rapidly declining 1 hour after flower opening. Pollen-ovule ratio was a quite low value (P/O=106). Floral syndromes were suitable to the mating habits of pre-anthesis cleistogamous. In natural or experimental populations, inter-flower pollination by insect were not observed, but intra-flower pollination were made by some small-sized insects (Tripidae). Pollen flow mediated by wind pollination was testified to be not existent. Results of artificial isolation or pollination showed that the fruit-sets after selfing/outcrossing were considerably high, but that outcrossing mechanism was short of in nature. Outcrossing rate of an experimental population was measured using isozyme genetic markers, the value estimated was, t=09%.