接种AMF对菌根植物和非菌根植物竞争的影响

Influence of arbuscular mycorrhizal associations on the interspecific competition between mycorrhizal and non-mycorrhizal plants

为了研究丛枝菌根真菌(arbuscular mycorrhizal fungus,AMF)对菌根植物与非菌根植物种间竞争的影响,以玉米(菌根植物)和油菜(非菌根植物)作为供试植物,分别进行间作、尼龙网分隔和单作,模拟这两种植物之间不同的竞争状态,接种丛枝菌根真菌Glomus intraradices和Glomus mosseae,比较菌根植物和非菌根植物的生长和磷营养状况,分析AMF侵染对植物种间竞争作用的影响。结果显示,与单作相比,间作模式下玉米的生物量及磷营养状况有所降低,但其菌根依赖性却有所提高。与不接种相比,接种处理显著降低了间作体系油菜根系的磷含量和磷吸收量,但趋于改善菌根植物玉米的磷营养状况。因此,接种AMF可以降低非菌根植物的磷营养状况及生物量,使得菌根植物的相对竞争能力明显提高,说明AMF在维持物种多样性方面有着重要的作用。

More than 85% of terrestrial plant species associate with arbuscular mycorrhizal fungi （AMF）. Most plant individuals stimulate nutrient availability through their fungal partner. Highly mycorrhizal-dependent plant species derive more benefits from AMF in comparison with plant species with a relatively low mycorrhizal dependency. Until recently, the effects of AMF on the competition between mycorrhizal and non-mycorrhizal plants （with high phosphate foraging ability） remained largely unclear, particularly in an environment with low phosphate bioavailability. Mycorrhizal effects on plant interactions are most likely due to alterations in the soil nutrient availability. AMF colonization could increase nutrient （particularly phosphate） availability for host plants and consequently increase plant biomass. The larger plants are then expected to be successful competitors. In the present study, maize （Zea mays L.） and rape （Brassica napus L.） plants were cultivated in three different interaction status, namely monoculture, intercropping and nylon net split. All the plants were inoculated with Glomus intraradices, Glomus mosseae or remained uninoculated. The strength of competition is measured as the reduction in biomass caused by the presence of a competitor. The results showed that maize growth and mineral nutrition was suppressed, while the mycorrhizal dependency increased to some extent, in intercropping compared with monoculture system. In intercropping system inoculation with G. intraradices and G. mosseae significantly decreased phosphorus concentration and content of rape roots compared with non-inoculation treatments, while in contrast mycorrhizal association improved phosphorus nutrition of maize plants. The experimental results clearly showed the beneficial effects of mycorrhizal associations on AMF host plants in competition with non-host plants. All these revealed that AMF may play an important role in structuring plant community and influencing plant biodiversity in ecosystems.