Mycorrhizal Networks Interacting with Litter Improves Nutrients and Growth for One Plant through the Vary of N/P Ratio under Karst Soil

Arbuscular mycorrhizae(AM)fungi affect nutrient uptake for host plants,while it is unclear how AM fungi interacting with soil litter affect plant growth and nutrient utilization through mycorrhizal networks in karst soil of deficient nutrients beyond the rhizosphere.An experiment was conducted in a microcosm composed of a planting compartment for Cinnamomum camphora seedlings with or without Glomus mosseae fungus(M+vs.M−)and an adjacent litter compartment containing or not containing additional litter material of Arthraxon hispidus(L+vs.L−),where the compartments are connected either by nylon mesh of 20μm or 0.45μm which either allow available mycorrhizal networks within the litter compartment or prevent mycelium entering into the litter compartment(N+vs.N−).Plant biomass and nutrients were measured.The results showed that the addition of litter changed the symbiotic process in mycorrhizal colonization,spore,and hyphal density,which when in association with the host plant then affected the biomass,and accumulations of N(nitrogen)and P(phosphorus)in the individual plant as well as root,stem,and leaf respectively.AM fungi increased N and P accumulations and N/P ratio in individual plants and plant tissues.A decrease of the N/P ratio of the individual plant was observed when AM fungus interacted significantly with litter through mycorrhizal networks in the litter compartment.The results indicate that the C.camphora seedlings benefited from litter in nutrient utilization of N and P through the vary of N/P ratio when accessing mycorrhizal networks.These findings suggest that mycorrhizal networks interacting with litter improve growth and nutrients of N and P for plants through the vary of N/P ratio in order to alleviate nutrient limitation under karst soil.

AM真菌和枯落物互作下两种喀斯特植物种间竞争较种内竞争更能促进植物养分利用

枯落物是植物养分获取和土壤养分转化的关键载体。丛枝菌根(Arbuscular mycorrhizae,AM)对植物养分摄取的影响已被广泛认知。然而,在养分亏缺的喀斯特生境中,不同竞争方式的植物如何通过AM真菌和枯落物利用养分尚不清楚。本研究对两种喀斯特适生植物构树(Broussonetia papyrifera)和云贵鹅耳枥(Carpinus pubescens)进行种内竞争和种间竞争种植处理,并通过幼套球囊霉(Glomus etunicatum)接种或不接种处理,以及土壤中添加或不添加两物种叶片混合枯落物处理,测定了植物生物量以及氮、磷、钾浓度等指标,研究植物的生长和养分利用。研究结果表明,AM真菌对两种植物养分摄取影响不同,AM真菌显著提高了种内和种间竞争下构树的养分摄取量,但降低了云贵鹅耳枥的养分摄取量。种间竞争下接种AM真菌,枯落物添加促进了云贵鹅耳枥对氮的摄取,抑制了构树对氮的摄取。接种AM真菌和添加枯落物条件下,种间竞争的构树对氮、磷和钾的摄取量及云贵鹅耳枥对氮的摄取量均高于种内竞争;种间竞争下两物种养分竞争力呈现明显差异,即构树对磷和钾养分竞争力显著提高,对氮则不显著;云贵鹅耳枥仅对钾的养分竞争力显著降低,对氮和磷则无显著影响。这些结果说明,在AM真菌与枯落物相互作用下,两种喀斯特植物种间竞争较种内竞争更能促进植物养分利用。