Plant interactions with single symbionts of nitrogen fixing bacteria or mycorrhizal fungi are well studied. However, less is known about how plants interact with multiple symbiont species. The aim of this study was to assess whether multiple symbionts had a synergistic effect on host plant performance compared with a single symbiont and whether increasing the number of non-specific fungal species would increase plant performance due to niche complementarity. Green alder (Alnus viridis ssp. crispa) were inoculated with non-specific ectomycorrhizal fungi (Lactarius torminosus, Lactarius theiogalus, Hebeloma crustuliniforme) alone or in combination, with and without Frankia, and grown in nutrient-poor soil. Frankia significantly increased plant growth by 48.5%, doubled the proportion of plants forming ectomycorrhizae, as well as increased root extracellular phosphatase activity by 8.8% compared to non-Frankia treatments. However, increasing number of fungal species decreased nodulated plant biomass. Plants that formed a Hartig net had reduced nodule number and nodule biomass allocation, as well as total nodule activity compared with plants with no Hartig net. Our results indicated that Frankia inoculation provided benefit for both host plants and ectomycorrhizal fungi in the nutrient-poor soil, while ectomycorrhizal fungi did not. These negative effects of mycorrhizal fungi are likely dependent on soil nutrient P availability.

中文翻译：

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Frankia和多种外生菌根真菌种类对低肥力土壤中Al木生长的影响

植物与固氮细菌或菌根真菌的单一共生体之间的相互作用已得到很好的研究。然而，关于植物如何与多种共生物种相互作用的了解还很少。这项研究的目的是评估与单一共生体相比，多种共生体对寄主植物的性能是否具有协同作用，以及增加非特异性真菌种类的数量是否会由于生态位互补而提高植物的性能。绿色桤木（桤木属贻贝SSP。皱）与非特异性外生菌根真菌（接种乳torminosus，乳theiogalus，Hebeloma crustuliniforme）单独或组合，具有和不具有弗兰克氏，并且生长在营养不良的土壤中。与非Frankia处理相比，Frankia显着提高了48.5％的植物生长，使形成菌根的植物比例增加了一倍，并且根部胞外磷酸酶活性提高了8.8％。但是，越来越多的真菌种类减少了结瘤植物的生物量。与没有Hartig网的植物相比，形成Hartig网的植物的根瘤数和根瘤生物量分配减少，总根瘤活性降低。我们的结果表明，弗兰克氏菌接种可在营养贫瘠的土壤中为寄主植物和外生菌根真菌提供益处，而外生菌根真菌则没有。菌根真菌的这些负面影响可能取决于土壤养分P的有效性。