长期连作农田土壤细菌群落结构和共现网络拓扑性质对土壤理化性质的响应

【目的】为探究长期连作土壤细菌群落结构和分子生态网络与土壤环境演化的关联性。【方法】本研究利用16S rRNA基因高通量测序技术，解析了湖南省浏阳市两块连作十二年农田(表现连作障碍的GD和健康的YA)土壤微生物群落组成结构和分子生态网络拓扑性质与土壤理化性质的关系。【结果】GD土壤总氮和有效磷含量显著高于YA，而土壤硝态氮和速效钾含量显著低于YA(P<0.05)。GD土壤细菌群落多样性高于YA，两地土壤细菌群落结构存在显著差异(P<0.01)，且与土壤pH和有效磷含量相关。进一步分析表明，GD土壤细菌群落之间比YA具有更复杂的生态网络，主要体现在能量代谢、碳循环和氮循环功能模块。【结论】综上所述，连作会引起土壤细菌群落多样性、组成结构和生态网络变化，这可能与土壤理化性质恶化、土壤肥力下降密切相关，进而影响作物生长发育。

Response of soil bacterial community structure and co-occurrence network topology properties to soil physicochemical properties in long-term continuous cropping farmland

Objective] To explore the relationship of soil bacterial community structure and molecular ecological network with soil environment in farmland with long-term continuous cropping. Methods] In this study, high-throughput sequencing of 16S rRNA gene was performed to reveal the correlation of soil microbial community structure and topological properties of molecular ecological network with soil physicochemical properties of two 12-year continuous cropping fields (GD with continuous cropping obstacle and healthy YA) in Liuyang, Hunan province. Results] The content of total nitrogen and available phosphorus in GD soil was significantly higher than that in YA soil, while the content of nitrate nitrogen and available potassium was significantly lower than that in YA soil (P<0.05). The bacterial diversity of GD soil was higher than that in YA soil, and the soil bacterial community structure was significantly different between GD and YA (P<0.01), which was related to soil pH and available phosphorus content. Soil bacterial community in GD had a more complex ecological network than that in YA, as manifested in the functional modules of energy metabolism, carbon cycle, and nitrogen cycle. Conclusion] Continuous cropping can cause changes in soil bacterial community diversity, structure, and ecological network, which may be closely related to the deterioration of soil physicochemical properties and soil fertility, and affects crop growth and development.