旱作区农田土壤AM真菌对长期有机无机施肥的响应

Response of arbuscular mycorrhiza fungi to long-term organic and inorganic fertilization in agricultural soils in dry farming regions

  • 摘要: AM真菌群落动态变化对于长期有效的土壤生态系统管理非常重要。为揭示旱作区农田土壤丛枝菌根(AM)真菌对长期有机、无机培肥管理的响应机制, 利用单因素随机区组设计, 基于连续11年的定位试验及高通量测序方法, 研究了不施肥(T0)、长期单施化肥(T1)、长期化肥与牛粪有机肥(T2)和长期化肥与羊粪有机肥(T3)对土壤的影响, 比较了土壤AM真菌群落组成及多样性间的差异, 探究了驱动土壤AM真菌群落组成及多样性变化的土壤环境因子及其相互作用效应。结果表明: 随培肥时间延长, 与T0处理相比, T2、T3处理的土壤全氮、有机质含量显著增加, pH显著下降(P<0.05); 与2018年相比, 2021年的T0、T1和T3处理土壤全磷和速效钾含量显著下降。有机无机肥配施下, 球囊霉属(Glomus)和类球囊霉属(Paraglomus)是土壤AM真菌的优势属, 但近明球囊霉属(Claroideoglomus)的相对丰度显著下降, 从优势属变为非优势属。近明球囊霉属较球囊霉属和类球囊霉属相对丰度而言, 更容易受长期培肥影响而发生显著改变。连续有机无机肥配施到2018年后, T2、T3处理的土壤近明球囊霉属和两性球囊霉属(Ambispora)的相对丰度与T0间有显著差异(P<0.05); 培肥至2021年后, T2、T3处理土壤近明球囊霉属和两性球囊霉属的相对丰度与T0处理间无显著差异。随培肥时间延长, 不同处理间土壤AM真菌群落的α多样性差异消失。NMDS分析结果表明: 长期培肥改变了土壤AM真菌群落的β多样性, 但T2与T3处理间土壤AM真菌群落相似性较一致。连续培肥改变了土壤AM真菌群落结构组成和多样性, 驱动AM真菌群落变化的土壤环境因子由土壤全氮、pH转变为土壤全磷。长期有机无机培肥没有同步提升土壤全磷、速效钾等主要理化性状。随培肥年限增加, 驱动土壤AM真菌群落结构和多样性变化的土壤因子发生了显著改变, AM真菌群落会随土壤环境因子的变化倾向于更加敏感的驱动因子。

     

    Abstract: The dynamics of arbuscular mycorrhiza (AM) fungal communities are important for effective, long-term soil ecosystem management. To reveal the response mechanisms of soil AM fungi to long-term combined applicatoin of organic and inorganic fertilizers in dryland farming regions, the effects of no fertilizer application (T0), long-term chemical fertilizer application (T1), long-term combined applicatoin of chemical fertilizer and cow manure organic fertilizer (T2), and long-term combined applicatoin of chemical fertilizer and sheep manure organic fertilizer (T3) on soil were investigated using a one-way randomized group design based on 11 consecutive years of locality testing and high-throughput sequencing methods. Differences in the composition and diversity of soil AM fungal communities were compared, and the factors affecting the soil environment and interaction effects that drive changes in soil AM fungal community composition and diversity were investigated. The results indicated that the soil total nitrogen and organic matter contents significantly increased, whereas the pH significantly decreased (P<0.05) under the T2 and T3 treatments compared to those under T0. Furthermore, compared with eight years of fertilization, 11 years of fertilization significantly decreased the total phosphorus and available potassium contents of the soil in the T0, T1, and T3 treatments. The dominant genera of soil AM fungi under organic and inorganic fertilization were Glomus and Paraglomus, respectively. However, the relative abundance of Claroideoglomus decreased significantly and changed from dominant to non-dominant. In contrast, the relative abundance of Claroideoglomus was more susceptible to long-term fertilization than that of Glomus and Paraglomus. After a period of eight years of combined applicaiton of organic and inorganic fertilizers, the relative abundance of AM fungi, specifically Claroideoglomus and Ambispora, in soils under T2 and T3 treatments was significantly different from that of T0 (P<0.05). Over the 11-years fertilization period, the relative abundances of Claroideoglomus and Ambispora under T2 and T3 treatments were not significantly different from those under T0. With the extension of fertilization time, differences in the α diversity of soil AM fungal communities disappeared among treatments. NMDS analysis showed that long-term fertilization changed the β diversity of the soil AM fungal community, but the soil AM fungal community was more similar between the T2 and T3 treatments. During the continuous application of fertilizer, significant changes were observed in the structural composition and diversity of the soil AM fungal community. Moreover, the soil environmental factors influencing changes in the AM fungal community shifted from soil total nitrogen and pH to soil total phosphorus. Long-term combined applicatoin of organic and inorganic fertilizers did not simultaneously improve the main physicochemical properties of soil, such as total phosphorus and available potassium. As the number of years of fertilization increased, the soil factors that drove changes in the structure and diversity of the soil AM fungal communities were significantly altered. The AM fungal community is more easily influenced by sensitive driving factors with changes in all soil environments.

     

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