三裂蟛蜞菊入侵对植物多样性的影响及其根提取物的抑草效应

Impacts of Wedelia trilobata Invasion on Plant Biodiversity and Inhibitory Effects of Its Root Extract on Test Plants

通过抽样法对样地植物进行调查并采集根系样品,采用物种多样性指数评价三裂蟛蜞菊(Wedeliatrilobata)对其入侵地植物群落的影响,以生测法探讨三裂蟛蜞菊根的4种有机溶剂萃取相对白菜(Raphanussativus)、羊蹄(Rumex japonicus)及三叶鬼针草(Bidens pilosa)的抑制效应。结果表明,三裂蟛蜞菊入侵地的丰富度指数(S)、Simpson多样性指数(D)、Shannon-Wiener多样性指数(H)和Pielou均匀度指数(J)均明显低于对照地,其差异均达显著或极显著水平,显示三裂蟛蜞菊具有强大的种间竞争优势;4种有机溶剂萃取相对供试植物的种子萌发与幼苗生长均有一定程度的抑制效应,其抑制强度表现为剩余乙醇相>正丁醇相>乙酸乙酯相>石油醚相,其中剩余乙醇相和正丁醇相处理组与对照组相比,3种供试植物各指标的差异均达到显著或极显著水平,尤其是1 000mg/L正丁醇对白菜、羊蹄和三叶鬼针草幼苗生长的综合抑制效应指数分别为-0.27、-0.23和-0.25,而剩余乙醇相则分别达到-0.40、-0.33和-0.26,初步证实根部分泌或残根分解是三裂蟛蜞菊抑草物质释放的主要途径之一。

On the basis of field investigation and sampling, invasive effects of Wedelia trilobata on plant communities were estimated through several species diversity indexes, and using bioassay to de termine the inhibitory strength of W. trilobata roots. The results showed that Richness index （S）, Simpson＇s diversity index （D）, Shannon-Weiner index （H） and Pielou evenness index （d） of treatment groups were significantly lower than those of control groups （P〈0.05 or P〈0.01）, which indicated that W. trilobata had a powerful interspecific competitiveness in the intruded community. Four donators （petroleum ether, ethyl acetate phase, normal butanol and remaining ethanol pha~.e） from W. trilobata＇s roots could inhibit seed germination and seedling growlh of three receptor plants （Raphanus sativus, Rumear japonicus and Bidens pilosa） to a certain extent, respectively, and the order of donators＇ inhibitory strength was remaining ethanol phase 〉 normal butanol 〉 ethyl acetate phase petroleum ether phase, and for all the indexes, the significant or extremely significant difference was observed between the treatment groups with the remaining ethanol or normal butanol phases and the control groups, especially, the synthetical inhibitory effect indexes （M） of the high concentration（1 000 mg/L） normal butanol phase on receptors＇ seedling growth were -0.27, -0.23 and -0.25, and for the same concentration remaining ethanol phase, M could reach -0.40, -0.33 and -0.26, respectively, which can basically demonstrate that root exudates or residual root decomposition is one of the main releasing pathways for inhibitory chemicals from W. trilobata, and there is a positive correlation between inhibitory strength and donor concentration. The research results can provide a foundation for isolation and identification of inhibitory chemicals from W. trilobata＇s roots.