Abstract:

The competitive succession of plants community is determined by feedback of interaction between plant and soil microbe. In order to confirm the role of soil microbe in the population establishment and expansion of Ageratina adenophora Sprengel, a vicious invasive weed in china,  the feedback effects of microorganisms in plant rhizosphere soil on growth of Ageratina adenophora Sprengel and 2 native plants were compared, Eupatorium lindleyanum DC. and Setaira viridis (L.) Beauv, by conducting the greenhouse pot experiment. A. adenophora and native plant soil were sterilized, added fungicide and no treated (control groups), respectively. The results showed that soil microorganisms in plant rhizosphere can produce a direct positive feedback effects on the growth of plants. The biomass of A. adenophora, E. lindleyanum and S. viridis decreased significantly after adding fungicide or sterilizing. There were no significant difference of AMF root colonization of E. lindleyanum and S. viridis between A. adenophora soil and native plant soil in control group, but AMF root colonization of E. lindleyanum and S. viridis in A. adenophora soil increased by 81.02% and 89.7% compared to native plant soil after adding fungicide, respectively. The PLFAs results also showed that the soil microbe communities of A. adenophora and native plants were apparently different. It was considered that the invasive plant, A. adenophora produced positive feedback to itself by affecting the soil microbe communities and function in invaded habits, subsequently contributing to its growth and population expansion.

Key words: Ageratina adenophora Sprengel, invasive plant, microbe feedback, PLFAs

摘要：

植物与土壤微生物互作及其反馈影响自然界植物群落的竞争性演替。为了明确土壤微生物在我国恶性入侵植物紫茎泽兰传入定殖后迅速竞争性扩张中的作用，通过接种植物根际微生物（紫茎泽兰和本地植物的根际土壤分别进行灭菌处理、添加杀真菌剂处理和无处理（对照））的盆栽法，比较了土壤微生物对紫茎泽兰和2种本地植物（林泽兰和狗尾草）的生长反馈效应。结果显示，根际土壤微生物对3种植物的生长均产生正反馈，紫茎泽兰、林泽兰和狗尾草在添加杀真菌剂处理或灭菌处理的生物量均比对照显著下降。林泽兰和狗尾草的根系AMF侵染率在对照的紫茎泽兰土壤和本地植物土壤中没有显著差异；但在添加杀真菌剂处理后，林泽兰和狗尾草的根系AMF侵染率在紫茎泽兰土壤中比在本地植物土壤中分别高出8102%和897%，说明紫茎泽兰土壤的真菌具有更强的正反馈作用。磷脂脂肪酸（PLFAs）分析土壤微生物群落多样性和功能微生物丰度的结果显示，入侵植物紫茎泽兰土壤和本地植物土壤的土壤微生物群落存在显著差异。综合推断认为，紫茎泽兰入侵后改变了土壤微生物群落结构，从而产生更有利于自身生长的正反馈，进而进一步促进了竞争性扩张。

关键词: 紫茎泽兰；入侵植物；微生物反馈；PLFAs