周年轮作休耕对土壤AMF群落和团聚体稳定性的影响

为探究轮作休耕对丛枝菌根真菌（AMF）群落组成及土壤团聚体稳定性的影响，以坡耕地红壤为研究对象，采用Illumina MiSeq高通量测序和湿筛法分别测定AMF群落组成和团聚体，研究了苕子轮作玉米（V-C）、豌豆轮作玉米（P-C）、冬闲-玉米（F-C）和周年休耕（F-F）这4个处理下AMF群落组成及其与土壤养分和团聚体稳定性之间的关系.结果表明，F-F、V-C和P-C处理的>2 mm团聚体含量、R_0.25及MWD均显著高于F-C （P<0.05），<0.25 mm团聚体含量均显著低于F-C （P<0.05）；F-F处理的ACE、Chao1和Shannon指数较F-C分别显著提高29.56%、35.78%和45.55%；球囊霉属（Glomus）为各处理AMF群落的优势属，盾巨孢囊霉属（Scutellospora）在各处理间差异显著（P<0.05）；PCoA分析发现，PC1和PC2分别累计解释了AMF群落组成差异的29.99%和22.40%；相关性分析表明，盾巨孢囊霉属与碱解氮（AN）和有机质（SOM）呈显著负相关（P<0.05），与速效钾（AK）呈显著正相关（P<0.05），球囊霉属与碱解氮呈显著正相关（P<0.05）；RDA分析表明，AMF多样性（Shannon指数）和盾巨孢囊霉属分别与>2 mm和2~1 mm团聚体含量显著正相关（P<0.05）.因此，周年休耕和苕子轮作玉米有利于提高土壤团聚体稳定性和改变AMF群落组成，研究结果为我国南方周年轮作系统提高土壤质量和推行合理轮作休耕模式提供理论依据和参考.

Effects of Annual Crop Rotation and Fallow on Soil AMF Community and Aggregate Stability

To investigate the effects of crop rotation and fallow on the community composition of arbuscular mycorrhizal fungi (AMF) and the stability of soil aggregates, AMF community and aggregates were measured using Illumina MiSeq high-throughput sequencing and wet screening methods in red soil of sloping farmland. The AMF community and its relationship with soil factors and aggregate stability were studied under the four treatments of vetch rotation corn (V-C), pea rotation corn (P-C), winter fallow corn (F-C), and annual fallow (F-F). The results showed that the aggregate content of >2 mm, R_0.25, and MWD in the F-F, V-C, and P-C treatments were significantly higher than those in F-C (P<0.05), and the aggregate content of <0.25 mm was significantly lower than that of F-C (P<0.05). The ACE, Chao1, and Shannon indexes of the F-F treatment were 29.56%, 35.78%, and 45.55% higher than those of the F-C treatment, respectively. Glomus was the dominant genus of AMF communities under all treatments, whereas Scutellospora showed a significant difference among the treatments (P<0.05). PCoA analysis showed that PC1 and PC2 together explained 29.99% and 22.40% of the difference in the AMF community composition, respectively. The correlation analysis showed that there was a significant negative correlation between Scutellospora and alkaline nitrogen (AN) and organic matter (SOM) (P<0.05), a significant positive correlation between Scutellospora and available potassium (AK) (P<0.05), and a significant positive correlation between Glomus and alkaline nitrogen (P<0.05). RDA analysis showed that AMF diversity (Shannon index) and Scutellospora were significantly and positively correlated with aggregate content >2 mm and 2-1 mm, respectively (P<0.05). Therefore, annual fallow and vetch rotation corn were conducive to improving the stability of soil aggregates and changing the composition of the AMF community. The research results provide a theoretical basis and reference for the annual rotation system to improve soil quality and implement a reasonable crop rotation and fallow pattern in southern China.