【作者】 王茜；

【导师】 金樑；

【作者基本信息】 兰州大学 ， 草学， 2016， 硕士

【摘要】 高寒草地退化是青藏高原面临的主要生态学问题之一,草地退化导致有毒植物逐渐替代优良牧草,植物种间竞争和种间互惠的相互作用直接影响草地的演替方向,优良牧草和有毒植物之间的相互作用受到生态学家的广泛关注。丛枝菌根（arbuscular mycorrhizae,AM）真菌可以调节植物种间的相互作用,但同样受到环境、宿主植物种类、真菌种类等生物因子和非生物因子的影响。本文拟围绕有毒植物根际AM真菌群落和AM真菌菌丝体网络对有毒植物与优良牧草之间的相互作用开展研究,以期阐明AM真菌在有毒植物和优良牧草种间竞争的功能。本研究主要包括三方面的内容,（1）在同一生境中,不同植物根际AM真菌的群落组成是否相同,如果不同,则其种类和数量是随着宿主植物种类的不同而变化?还是随着退化程度的加剧而变化?（2）AM真菌菌丝体网络是否对菌根植物和非菌根植物种间相互作用有影响?（3）在不同P梯度下,植物在受到AM真菌菌丝体网络的影响时是否同时影响自身对P元素吸收?主要研究结果如下:1)本次试验通过研究青藏高原高寒轻度退化草地和中度退化草地中六种聚集分布的有毒植物风毛菊（Saussurea japonica）、独一味（Lamiophlomis rotata）、秦艽（Gentiana macrophylla）、乳白香青（Anaphalis lactea）、小花草玉梅（Anemone rivularis）、火绒草（Leontopodium japonicum）根际土壤的AM真菌种类、数量、根系侵染率、测定其AM真菌群落的生物多样性指数、相似性指数和丰富度指数,研究得出在同一生态环境中,AM真菌群落的分布与宿主植物之间存在一定的相关性。本次试验共分离出AM真菌9属21种,球囊霉属物种出现的频率最高,其中苏格兰球囊霉（Glomus caledonium）的频率最高,达到94.4%;其次是黏质球囊霉（Glomus viscosum）,出现频率为77.8%。风毛菊和秦艽根际AM真菌物种丰富度分别为11、10,乳白香青、火绒草根际AM真菌物种丰富度次之,均为8;而独一味、小花草玉梅根际AM真菌物种丰富度较小,分别为5种和4种。6种有毒植物根际AM真菌群落球囊霉属的重要值表现为:乳白香青>秦艽>小花草玉梅>风毛菊>火绒草>独一味。秦艽和风毛菊、乳白香青和风毛菊的AM真菌群落结构相似性高。而小花草玉梅与乳白香青的AM真菌群落结构相似性最低。2)在温室条件下研究AM真菌菌丝体网络对有毒菌根植物风毛菊、非菌根植物珠芽蓼（Polygonum viviparum）与两种优良牧草垂穗披碱草（Elymus nutans）、草地早熟禾（Poa pratensis）种间竞争的影响,通过无菌丝（NM）处理、切断菌丝（CM）处理以及完整菌丝（M）处理得出,AM真菌菌丝体网络对优良牧草的影响不显著,但是对有毒植物的生长产生重要影响。从株高、根长、生物量的分析得出,AM真菌减缓垂穗披碱草、草地早熟禾与风毛菊之间的竞争作用,促进风毛菊的生长。但加剧了珠芽蓼和优良牧草之间的竞争。特别是在CM处理中,珠芽蓼的生物量显著增加,达到最大值,而优良牧草的生物量显著降低。（3）在温室条件下研究不同P浓度梯度下,AM真菌菌丝体网络对风毛菊与三种优良牧草种间竞争的影响。试验设计三个影响因子:菌丝体网络、不同P梯度以及不同宿主植物,结果表明AM真菌菌丝体网络促进了有毒植物风毛菊和优良牧草垂穗披碱草、草地早熟禾、高山嵩草（Kobresia pygmaea）之间表现为促生的相互作用。而随着土壤中P的增加,垂穗披碱草、草地早熟禾与风毛菊的组合中,菌丝体网络显著提高了垂穗披碱草、草地早熟禾与风毛菊的生物量。而在20mg kg^-1的梯度下,风毛菊和高山嵩草的组合中,AM真菌菌丝体网络抑制了不同植物之间的相互作用,表现为竞争效应,在200 mg kg^-1的梯度下,风毛菊和高山嵩草的相互作用关系为促进关系。本研究结果表明,在任何P梯度下,风毛菊吸收P元素的能力显著高于其他三种优良牧草,三种优良牧草吸收P元素的能力分别为草地早熟禾>垂穗披碱草>高山嵩草。更多还原

【Abstract】 The poisonous plants replace gradually the herbage in degradated grassland on the Tibetan plateau.The interaction between poisonous plant and herbage affect directly the direction of the succession of grassland such as competition and mutual.Arbuscular mycorrhizal(AM)fungi is one of the most important soil microorganisms in terrestrial ecosystems and can regulate interaction between plants,but also be influenced by the biological factors and non-biological factors such as the environment,the host plant species and strains of the fungi.So,in this paper,we research the poisonous plant rhizosphere of AM fungi community and the results of AM fungi mycelium network influences interaction relationship between poisonous plants and the herbage.The main results were as follows:(1)There was a tendency that the distribution of AM fungi community with the host plantsin the same ecological environment.We isolated 21 kinds of AM fungi belong to 9 species in this experiment,the frequencies of Glomus genera were the highest,Glomus caledonium had the highest frequency,94.4%;Followed by Glomus viscosum frequency of 77.8%.Saussurea japonica‘s and Gentiana macrophylla‘s rhizosphere of AM fungi species richness were 11 and 10 respectively,Anaphalis lactea‘s and Leontopodium japonicum‘s rhizosphere of AM fungi species richness were 8 in the medium level.And Lamiophlomis rotata‘s and Anemone rivularis‘s rhizosphere of AM fungi species richness were the least,is 5 and 4 respectively.The Glomus genera important worth of Anaphalis lacteais the highest in 6 kinds of poisonous plant rhizosphere of AM fungi community.AM fungi community structure similarity of Gentiana macrophylla and Saussurea japonic,Anaphalis lactea and Saussurea japonica was high.AM fungi community structure similarity of Anemone rivularis and Anaphalis lactea was the lowest;(2)AM fungi had the important impact on poisonous plants,through the influence of AM fungi mycelium network was not significant through the NM,CM and M treatment.From the analysis of the plant height,root length and biomass,AM fungi to slow down the competition effect of Elymus nutans,Poa pratensis combine with Saussurea japonica and promote the growth of Saussurea japonica.Also contributed to the competition between Polygonum viviparum and herbage.Especially in dealing with the CM treatment,Polygonum viviparum‘s biomass increased significantly,and reached a maximum,and herbage biomass decreased significantly at this time.(3)AM fungi mycelium network did promote the interactions between poisonous plant Saussurea japonicaand Elymus nutans,Poa pratensis,Kobresia pygmaea.Plant materials accessed near P element by AM fungi mycelium network under any P gradient,Saussurea japonica gain the ability of the P element is significantly higher than the other kinds plant,and three kinds of herbage results to gain the ability of the P element respectively: Poa pratensis>Elymus nutans>Kobresia pygmaea.They were characterized by mutual benefit.And with the increase of P through mycelium network in the soil.And the group of Saussurea japonicaand Kobresia pygmaea was inhibited by AM fungi mycelium network in the interaction under the gradient of P20 and showed the competition relations.But the group of Saussurea japonica and Kobresia pygmaea shows the mutual benefit relations under the gradient of P200.更多还原