长期施用氮肥和磷肥对东北黑土丛枝菌根真菌群落组成的影响

【目的】丛枝菌根(Arbuscular mycorrhizae,AM)真菌在促进作物养分吸收、提高作物抗病和抗逆性等方面具有重要意义,探讨长期施用化学氮肥和磷肥对东北黑土AM真菌的影响及其主效环境因子,为进一步揭示AM真菌对化肥的响应机制,指导农田施肥以及利用AM真菌提高土壤养分有效性提供依据。【方法】以长期定位试验为平台,选取5种不同处理:不施肥(CK),单施常量氮肥(N_1),混施常量氮肥和磷肥(N_1P_1),单施2倍常量氮肥(N_2),混施2倍常量氮肥和磷肥(N_2P_2)。采用Illumina Miseq高通量测序技术研究连续施用37年氮肥和磷肥的AM真菌群落组成差异,并对AM真菌群落组成与环境因子进行相关性分析。【结果】随着氮、磷施用量的增加,黑土p H和速效钾含量显著降低,而全氮、硝态氮、铵态氮和有机质含量显著提高。单施氮肥(N_1和N_2)对黑土中AM真菌多样性影响不显著(P0.05);然而氮、磷混施(N_1P_1和N_2P_2)显著降低黑土中AM真菌多样性(P0.05)。土壤中AM真菌以Glomeraceae科为主,占AM真菌45.5%。在属水平上,施肥降低Funneliformis和Septoglomus丰度,而提高Paraglomus丰度;在N_1和N_2基础上施磷显著提高Glomus和Funneliformis丰度,而降低Gigaspora和Paraglomus的丰度。非度量多维度分析表明,长期施用氮、磷肥改变了土壤中AM真菌群落组成。不施肥处理、单施氮肥处理和氮、磷混施处理AM真菌群落差异显著,且磷肥影响较为显著。冗余分析表明,土壤p H,有效磷含量是影响黑土中AM真菌群落组成的主效环境因子(P0.05)。【结论】长期施用氮肥以及氮、磷肥混施改变了黑土中AM真菌群落组成,单施氮肥对黑土中AM真菌多样性影响不大,而氮、磷肥混施降低其多样性,施肥导致的土壤p H和有效磷含量变化是主要因素。

Influence of Long-Term Nitrogen and Phosphorus Fertilization on Arbuscular Mycorrhizal Fungi Community in Mollisols of Northeast China

【Objective】Arbuscular mycorrhizal (AM) fungi, which form symbiotic relationships with the majority of land plants, can provide plants with critical nutrients, act as protectants against phytopathogens, and help plants withstand stresses. In order to clarify the effects of different doses of nitrogen (N) and phosphorus (P) fertilization on the community composition and reveal the main driving factors of AM fungi, a long-term fertilizer experiment (37-year) was set up in mollisols of northeast China. This study would provide evidence for further enhancing fertilization and using AM fungi to increase availability of soil nutrients for plants.【Method】Base on a long-term fertilization field experiment, Illumina MiSeq platform were used to analyze the effects of different N and P fertilization on AM fungal community. The soil samples were collected and analyzed from five fertilization regimes: No fertilizer (CK), normal N fertilizer (N₁), normal N plus normal P fertilizers (N₁P₁), duple N fertilizer (N₂), and duple N plus duple P fertilizers (N₂P₂). A correlation analysis was used to reveal the main important factors for determining the AM fungal community composition. 【Result】 Long-term N and P fertilization decreased soil pH and available K, however, which increased total N, KCl-extractable NO₃^- and NH₄⁺, and organic matter. N-fertilization (N₁ and N₂) did not significantly change soil AMF diversity (P＞0.05), while N- plus P-fertilization (N₁P₁ and N₂P₂) decreased it compared with CK (P＜0.05). Glomeraceae was the most abundant family in soils, accounting for 45.5% of all AM fungi. In genus level, all fertilization decreased the relative abundance of Funneliformis and Septoglomus, whereas increased Paraglomus;N- plus P-fertilization increased the relative abundance of Glomus and Funneliformis, but decreased Gigaspora and Paraglomus. Nonmetric Multidimensional Scaling analyzed result showed that the community composition in no fertilization, N fertilization, and N- plus P-fertilization was significantly different with each other. And a redundancy analysis indicated that soil pH, concentration of available P were the main environment factors (P＜0.05) affecting the AM fungal community variation. 【Conclusion】 Our research demonstrated that long-term fertilization changed soil AM fungal community composition in mollisols. N-fertilization did not change AM fungal diversity while N- plus P-fertilization decreased it. It was concluded that soil pH and available P concentration were the main factors affecting AM fungal community variation.