长期不同施肥对棕壤AM真菌群落结构的影响

【目的】探明长期不同施肥条件下玉米–大豆轮作棕壤丛枝菌根 (Arbuscular mycorrhizal, AM) 真菌群落结构的变化及其影响因素。【方法】以沈阳农业大学棕壤肥料长期 (38年) 定位试验耕层土壤 (0—20 cm) 为材料，于2016年4月选取其中6个施肥处理:1) 不施肥 (CK)；2) 单施化学氮肥 (N)；3) 施用化学氮磷肥 (NP)；4) 施用化学氮磷钾肥 (NPK)；5) 单施有机肥 (M)；6) 有机肥和化学氮磷肥配施 (MNP)。采用PCR-DGGE和克隆测序，分析了棕壤AM真菌群落结构，并结合环境因素进行冗余分析和典型对应分析。【结果】施用有机肥处理土壤有机碳 (TOC)、全氮 (TN)、全磷 (TP)、全钾 (TK)、碱解氮 (AHN)、有效磷 (AP)、速效钾 (AK)、可溶性有机碳 (DOC) 含量显著高于单施化肥和不施肥处理，且趋势表现为有机肥处理 > 化肥处理 > CK；与CK相比，单施化肥处理显著降低了土壤pH值，施用有机肥处理显著提高了土壤pH值。长期施肥显著改变了土壤中的AM真菌孢子密度，施用有机肥处理的孢子密度显著高于单施化肥处理和不施肥处理。冗余分析结果表明，土壤pH与AM真菌多样性指数和均匀度均呈显著负相关，而孢子密度与AP、TK、AHN呈显著正相关，AM真菌多样性指数与孢子密度则不相关。聚类分析表明长期不同施肥将棕壤中AM真菌分为两大类群，分别为不施肥区和施肥区，其相似度仅为42%。通过割胶克隆测序得出从土壤样品中分离的AM真菌种群主要为球囊霉菌，典型对应分析表明AP、AK、TOC、NH ₄+-N显著影响AM真菌的群落组成。【结论】长期定位施肥改变了棕壤的理化性质，从而对AM真菌的群落结构产生了显著影响。

Influence of long-term fertilization on structures of arbuscular mycorrhizal fungi community in a brown soil

【Objectives】This study aims to explore changes of community structures of AM (Arbuscular mycorrhizal) fungi and to find out main factors of affecting the structures in a corn-soybean rotation system and a long-term fertilization trial for 38 years in a brown soil.【Methods】Soil samples (0–20 cm) were taken from six treatments of the long-term fertilization trial in April 2016, 1) no fertilization (CK); 2) chemical N input (N); 3) chemical N and P input (NP); 4) chemical N, P and K input (NPK); 5) pig manure (M); and 6) pig manure plus chemical N and P(MNP). Soil samples were analyzed using PCR-DGGE, cloning and sequencing techniques, and the relationship between community of AM fungi and environmental factors was analyzed using the redundancy analysis and canonical correlation analysis.【Results】The results showed that the contents of total organic C (TOC), total N (TN), total P (TP), total K (TK), alkali-hydrolysable N (AHN), available P (AP), readily available K (AK) in the organic fertilizer treatments were significantly higher than those in the CK treatment and chemical fertilizer treatments, and the trend is: organic fertilizer > chemical fertilizer > CK. Compared with the CK treatment, the chemical fertilizer treatments decreased soil pH, while the organic fertilizer treatments increased soil pH. The redundancy analysis showed that pH had significantly negative correlation with the diversity and evenness of AM fungi. AP, TK and AHN had significantly positive correlation with spore density. There was no correlation between AM fungi diversity index with spore density. The cluster analysis showed that the community structures of AM fungi were divided into two groups, namely, non fertilization group and fertilization group, and their similarity was only 42% under the long-term fertilization. The result of sequencing showed that AM fungi species isolated from soil samples were mainly glomeromycota. The canonical correlation analysis showed AP, AK, TOC and NH ₄+-N significantly influenced the species of AM fungi.【Conclusions】The long-term fertilization changed community structures of AM fungi by changing soil physicochemical properties.