减磷配施有机肥对丛枝菌根真菌群落的复杂度和稳定性的短期效应

Short-term effects of application of reduced phosphorus fertilizer combined with manure on the community complexity and stability of arbuscular mycorrhizal fungi

摘要:

【目的】探究减磷配施有机肥条件下土壤中丛枝菌根（arbuscular mycorrhiza，AM）真菌群落特性、网络复杂性及群落的稳定性之间的关系，揭示有机肥替代背景下，土壤理化性质与AM真菌的群落结构对网络特征和群落稳定性的短期效应。【方法】在2012年开始的无机磷肥长期定位试验的基础上，于2018年实施减磷配施有机肥裂区试验，共设6个处理：施无机磷0、75、150 kg/hm²；无机磷肥施用量减少30%，即0、52.5、105 kg/hm²，并配施有机肥（猪粪）3 187 kg/hm²，每个处理重复3次。通过高通量测序和生物信息学分析，探究减磷配施有机肥对土壤中AM真菌群落的网络特征及稳定性的短期效应。【结果】相比于无机磷施用，减磷配施有机肥整体上降低了AM真菌群落的α多样性，各处理中的AM真菌优势类群均为球囊霉属（Glomus）和类球囊霉属（Paraglomus）。网络的平均度、平均加权度在无机磷肥及减磷配施有机肥处理中均在适量施磷下达到最大值，且无机磷肥处理大于减磷配施有机肥处理；网络负相关连接线数在无机磷肥处理中随施磷量增加而增加，而在减磷配施有机肥处理中随施磷量增加而减少。减磷配施有机肥通过抑制AM真菌群落间正相互作用来提高负正凝聚力比值，从而促进群落稳定性。相比于AM真菌的指示物种（indicator species）和关键类群（keystone taxa），优势类群（dominant taxa）与AM真菌群落的稳定性密切相关。【结论】在酸性紫色土中，短期减磷配施有机肥通过改变土壤pH、速效磷和有机质，调控AM真菌群落的α多样性和优势类群，进而影响AM真菌群落的网络复杂度和群落稳定性。

Abstract:

[Objective] To investigate the community characteristics, network complexity, and community stability of arbuscular mycorrhizal fungi (AMF) in the soil applied with reduced phosphorus (P) fertilizer combined with manure, and reveal the short-term effects of soil properties on the network characteristics and community stability of AMF community in the context of manure substitution for chemical fertilizers. [Methods] On the basis of the long-term inorganic P fertilizer application experiment started in 2012, a split plot experiment was designed with the application of reduced P fertilizer combined with manure and started in 2018. Six treatments were designed:inorganic P supply at 0, 75, and 150 kg/hm² and 30% reduction in inorganic P fertilizer (i.e., 0, 52.5, and 105 kg/hm²) combined with manure at 3 187 kg/hm², with three replicates for each treatment. High-throughput sequencing and bioinformatics analysis were employed to explore the short-term effects of application of reduced P fertilizer+manure on the network characteristics and stability of the AMF community in soil. [Results] The alpha diversity of AMF decreased in the case of application of reduced P fertilizer+manure compared with that in the case of inorganic P fertilization. Glomus and Paraglomus were the dominant taxa of AMF in each treatment. The average degree and average weighted degree of the network reached the maximums under the appropriate amount of P fertilizer, and were higher in inorganic P treatments than in reduced P fertilizer+manure treatments. The number of negative correlation links in the network increased with the increase in P application in inorganic P treatments and decreased with the increase in P application in reduced P fertilizer+manure treatments. The application of reduced P fertilizer+manure improved the stability of AMF community by increasing the negative/positive cohesion ratio. Compared with indicator species and keystone taxa, dominant taxa are closely associated with the stability of AMF community. [Conclusion] In acid purple soil, short-term application of reduced P fertilizer+manure regulated the alpha diversity and dominant taxa of AMF by changing soil pH, available P, and soil organic matter, thereby affecting the network complexity and stability of AMF community.