不同鱼塘-稻蟹复合种养模式下稻田土壤细菌群落结构研究

Impact of Fishpond-Rice-Crab Integrated Co-culture Model on Structure of Soil Bacterial Community in Rice Fields

摘要:

针对宁夏地区稻蟹种养水资源短缺和鱼塘养殖尾水处理难等问题，以传统黄河水灌溉稻田的稻蟹种养模式（CK）为对照，探究鱼塘-稻蟹复合种养模式（RS）与CK种养模式对稻田土壤环境因子以及细菌群落结构影响的异同，并揭示细菌群落结构的主要影响因子。基于16S rRNA高通量技术对CK模式与RS模式4—8月稻田土壤的细菌群落组成、结构差异性及其与土壤指标之间的关系进行分析。结果表明：鱼塘-稻蟹复合种养模式降低了稻田土壤pH值，提高了铵态氮和有效磷含量；改变了稻田土壤细菌物种丰富度。Chaol和Shannon指数4月最高，5月较低。4—8月优势菌门为变形菌门、拟杆菌门、厚壁菌门，优势菌属均为假单胞菌属。鱼塘-稻蟹复合种养模式4—8月假单胞菌属累积相对丰度降低了7.61个百分点，硫杆菌属提高了4.94个百分点，Unspecified_Bacteria菌属增加了1.83个百分点，其他菌属变化在±1个百分点内。冗余分析表明全钾、铵态氮、总氮、有机质含量以及pH值对相对丰度排序前十的细菌菌门影响最大；全钾含量对前十菌门相对丰度的解释度最高（23.67%），且与变形菌门相对丰度呈正相关，与其他菌门均呈现负相关，硝态氮含量与相对丰度前十菌门主要呈正相关。鱼塘-稻蟹复合种养模式对改善土壤环境与结构、丰富细菌物种多样性和优化细菌群落结构效果明显。

Abstract:

In order to address the problems of tailwater treatment in fishpond aquaculture in the Ningxia region and the scarcity of water resources in rice-crab co-culture systems, the bacterial community structure and soil environmental factors of a fishpond-rice-crab integrated co-culture model (RS) were compared and contrasted with the traditional Yellow River-irrigated rice-crab co-culture model (CK) as control. The primary environmental factors influencing alterations in the organization of the bacterial population were also identified. The composition and structural variations of soil bacterial communities under both CK and RS models from April to August were examined, together with their associations with soil physicochemical markers, using 16S rRNA high-throughput sequencing techniques. The findings demonstrated that the RS model changed the species richness of soil bacteria while decreasing soil pH value and raising ammonium nitrogen and accessible phosphorus levels. The greatest Chao1 and Shannon diversity indices appeared in April, while the lowest appeared in May. Proteobacteria, Bacteroidota, and Firmicutes were the most prevalent bacterial phyla from April to August, with Pseudomonas being the most prevalent genus. The cumulative relative abundance of Pseudomonas was decreased by 7.61 percentage points, Thiobacillus was increased by 4.94 percentage points, and Unspecified_Bacteria was increased by 1.83 percentage points as compared with the CK model;changes in other taxa were within ±1 percentage point. Redundancy analysis showed that the most important variables influencing the top ten bacterial phyla were pH value, total nitrogen, ammonium nitrogen, total potassium, and organic matter concentration. Total potassium exhibited the highest explanatory power (23.67%) among them, exhibiting negative relationships with other phyla and positive correlations with Proteobacteria. In general, the top ten phyla showed a positive correlation with nitrate nitrogen concentration. As a result, the fishpond-rice-crab integrated co-culture paradigm optimized the makeup of the bacterial community, boosted bacterial species diversity, and greatly improved soil environmental conditions and structure.