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文摘
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对青藏高原东部麻花艽(Gentiana straminea)海北居群的传粉生态学进行了3a连续的观察和实验。试验表明自然去雄、人工自交和杂交处理均结实，而人工去雄套袋和自然套袋不结实。麻花艽自交亲合，但必须依赖传粉媒介才能完成授粉过程，不存在无融合生殖。野外捕捉到14种访花昆虫，它们分别属于2个纲，7个目，8个科。观察和分析了各种昆虫的访花行为后，认为苏氏熊蜂(Bombus sushikini)是麻花艽有效而稳定的传粉者。测量表明麻花艽花蜜通道的深度和苏氏熊蜂的舌长基本吻合。苏氏熊蜂的访花频率在lO：00～12：00，13：00～15：00和16：00～18：OO时间段没有差别，单花的访花频率为0．005次／(花·rain)。和其它高山植物相比，青藏高原高山植物麻花艽的访花频率较高。熊蜂传粉和高频率的访花维持了麻花艽在极端寒旱的青藏高原环境下的有性生殖。此外，高频率的访花对于维持该地区高山植物的生殖保障具有重要的现实意义，但是否具有普遍性，还有待研究更多的高山代表类群。 |
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其他语种文摘
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The reproductive success in flowering plants, measured as seed set, may depend on a number of factors, including pollen limitation, resource limitation, predation, and physical environment. Resource limitation is probably the most important factor in flowering plants as a whole. But in alpine species dependent on insects for pollination, pollen limitation may be more important, since pollinator^ generally are less reliable. In this study, we studied the pollination ecology of Gentiana straminea, an alpine perennial in the Qinghai-Tibet Plateau with a preference to alpine meadow for three consecutive years. The results of manual self-pollination and outcrossing demonstrated that G. straminea is strongly self-compatible because we did not find significant difference in both seed number and seed sets between these two treatments. Furthermore, the breeding experiments found that autonomous self-pollination and agamospermy do not exist in this species for isolated flowers with or without emasculation produced no seed. These manual experiments indicated that G. straminea is pollinator-dependent for seed set. The natural seed number and seed sets monitored for three years were always high implying that there are stable and enough pollinators in the studied population in spite of the arid habitats. Visitors consist of about 14 species, belonging to two classes, seven orders and eight families. According to the visiting behaviors of these various insects, Bombus sushikini is suggested to the dependable and effective pollinators of G. straminea. Other insects, such as spiders, beetles, ladybugs, stink
bugs, thrips, and flies, are not pollinators of this species not only because of their low visiting frequency but also because they could not fit very well with the relatively large flower and touch both anthers and stigmas. Another bumblebee species, B. kashmirensis, also visited G. straminea in the studied population, but it probed the corolla base for nectars from outside without touching anthers and stigmas. Although two other bumblebee species, B. filchnera and B. woltoni, had similar visiting behavior and pollination effects with B. sushikin, their visit frequencies were especially low. Only two B. filchnera and one B. woltoni were observed to visit and pollinate G. straminea for all monitored hours in the past three years and they should be considered as accidental pollinators. In addition, the tongue length of the effective pollinator, B. sushikini, agrees well with
the depth of the corolla tube of G. straminea for foraging nectar. We did not find the difference of visiting frequency of this bumblebee during three different time intervals, 10:00~12:00, 13:00 ~ 15 :00 and 16:00 ~ 18:00. Its visiting frequency for all recorded time averaged 0. 005 per flower per minute, which is obviously higher than those recorded for alpine plants from other areas. Such a high frequency is important for maintaining the seed set and reproductive assurance of G. straminea. However, it needs a further test that whether this high visiting frequency also occurs in other alpine species in the Qinghai-Tibet Plateau. |
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来源
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生态学报
,2004,24(2):215-220 【核心库】
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关键词
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麻花艽
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地址
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中国科学院西北高原生物研究所, 青藏高原生物进化与适应开放实验室, 西宁, 810008
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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1000-0933 |
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基金
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国家自然科学基金
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国家自然科学基金
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中国科学院知识创新工程重要方向项目
;
国家教育部高等学校全国优秀博士学位论文专项资金
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文献收藏号
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CSCD:1630808
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