丛枝菌根真菌对入侵植物南美蟛蜞菊生长及竞争力的影响

【背景】丛枝菌根真菌(arbuscular mycorrhizal fungi，AMF)能促进植物的养分吸收及生长发育。入侵中国华南地区的外来入侵植物南美蟛蜞菊(Wedelia trilobata)常分布于养分匮乏的荒地，却能迅速生长并排挤本地植物而快速扩张领地。【目的】探究丛枝菌根真菌是否促进南美蟛蜞菊的生长与竞争能力。【方法】采用南美蟛蜞菊及其同属本地植物蟛蜞菊(Wedelia chinensis)的盆栽对比控制试验，并设置接种及不接种AMF变形球囊霉(Glomus versiforme)、不同磷营养水平以及单种或混种的种植方式3种处理对两种植物的生长及竞争能力进行比较。【结果】AMF均能侵染上述两种植物，并且AMF对南美蟛蜞菊根系的侵染率显著高于其对蟛蜞菊根系的侵染，尤其是在低磷水平下南美蟛蜞菊的菌根侵染率更高，而且AMF的侵染显著促进了低磷水平下南美蟛蜞菊的生长及其对蟛蜞菊的竞争能力。【结论】丛枝菌根真菌能够促进南美蟛蜞菊的生长，增强其对本地植物的竞争优势，该效应很可能对外来植物南美蟛蜞菊的成功入侵产生一定的作用。

Effects of arbuscular mycorrhizal fungi on the growth and the competition of an invasive plant Wedelia trilobata

Background] Arbuscular mycorrhizal fungi (AMF) can promote the nutrient absorption and the growth and development of plants. An invasive plant Wedelia trilobata, invaded in the South China, often distributes in nutrient-poor wasteland, but still grows and expands rapidly. Objective] To explore whether arbuscular mycorrhizal fungi play an important role in the growth and competition of W. trilobata. Methods] A greenhouse control experiment was conducted using W. trilobata and its native congener W. chinensis. The effects of AMF (Glomus versiforme), different phosphorus nutrition, monoculture or mix-culture on the growth and the competition abilities of these two plants were investigated. Results] Both these two plants were infected by AMF, and the colonization percentage of AMF in W. trilobata was significantly higher than that in W. chinensis, especially under low phosphorus. AMF significantly improved the growth and the competition ability of W. trilobata under low phosphorus conditions. Conclusion] Interactions with AMF not only promote the growth of W. trilobata, but also enhance its competitive advantage. This effect is likely to significantly contribute to the successful invasion of W. trilobata.