长期轮作条件下黑土微生物区系演变特征与应答机制

The long-term continuous cropping is an important reason for the decline of soil quality in the black soil region. Rational rotation system directly affects the soil microbial biomass in the transformation process of soil material and it`s also an effective measure to build a healthy soil micro ecology. This study is based on three long term location test station of black soil in Northeast china（38-year black soil experiment station and 22-year maize/soybean continuous and rotation experiment stations）. Explore the evolution of long-term rotation under the condition of the soil microbial community composition characteristic and analysis the microbial community composition which is helpful to inhibit soil pathogenic and improve crop yield by using high-throughput sequencing technology. Analysis the response relationship between soil microbial flora and crop rotation, soil organic matter fractions, exogenous fertilizers and crop nutrient demand characteristics by using stable isotope tracer labeling. Using qualitative and quantitative analysis of the characteristics of soil microbial flora in black soil to explain the response mechanism of microbial flora in the long-term rotation cultivation mode. The results can provide a scientific and reliable theoretical basis for the establishment of a crop rotation system in High Yield Black Soil and the establishment of a benign evolution of soil microbial flora.

作物长期连作是导致黑土区土壤质量下降的重要原因，合理的轮作体系直接影响到土壤微生物参与的土壤物质转化过程，也是构建健康土壤微生态的有效措施。本研究以黑龙江省农科院38年黑土长期肥力监测定位试验和22年玉米、大豆连作和轮作定位试验土壤样本为材料，利用高通量测序等技术研究小麦-玉米-大豆12个长期轮作周期内施肥及大豆、玉米22年连作、轮作对土壤细菌群落组成的演变特征，分析有利于抑制土壤病源发生、作物高产的土壤细菌群落构成。通过稳定性同位素示踪标记，解析黑土碳氮循环土壤细菌区系与轮作的作物种类、土壤有机质组分、外源肥料及作物养分需求特征等主要因子之间的响应关系，利用土壤细菌区系特征的定性、定量表达分析，阐述长期轮作栽培模式下土壤细菌区系应答机制，为黑土作物高产高效的轮作制度建立、健康良性演变的土壤微生区系构建提供科学可靠的理论基础。

当前黑土区作物连作现象较为普遍，构建合理轮作模式是构建健康、提升作物产量的有效措施。本研究通过分析不同轮作模式、不同施肥条件下的土壤微生物群落组成演变特征，解析土壤微生物对轮作模式的响应机制，为黑土作物高产高效的轮作制度建立提供科学依据。研究结果表明，长期施用无机肥导致黑土中真菌的数量增加，使土壤由“细菌型”转化为“真菌型”，而有机无机配施可以改变这种变化趋势。施肥改变了真菌优势菌的相对丰度，长期有机无机配施的真菌组成结构更有利于降低土传病害发生率。黑土区作物连作显著改变土壤中的细菌群落结构组成，使大豆和玉米连作的细菌群落结构组成类似。从真菌相对丰度及多样性水平出发，北部黑土区以大豆-玉米-玉米的轮作方式更利用防止作物连作引起的土传病害发生。大豆-玉米轮作条件下，Proteobacteria、Firmicute、Patescibacterias促进了土壤富里酸中类腐殖酸物质、微生物代谢产物的生成与积累；Acidobacteriota促进了土壤富里酸中类腐殖酸物质、微生物代谢产物的分解。Patescibacteria、Verrucomicrobiota、Bacteroidota是影响土壤富里酸组分的主要因子。与连作相比，黑土区大豆玉米轮作可有效地提高土壤总养分含量，以玉米-大豆-大豆轮作方式最为显著。铵态氮、速效钾是影响细菌、真菌的多样性与丰富度的主要因子。土壤理化性质、作物季和施肥分别解释了真菌群落变化的 27.16%，4.49%和 2.41%，土壤性质和施肥共同解释量为33.88%，土壤性质和作物交互作用解释量为51.84%，施肥和作物交互作用解释量为 6.90%。