稻田土壤微生物群落对稻鳖共作模式的响应特征

稻鳖共作是一种绿色、高效的生态农业种养模式，然而有关共作模式对稻田土壤微生物群落结构与功能特征的影响及其驱动因子的研究鲜有报道。为此，该研究以水稻单作（RM）和稻鳖共作（RT）处理的稻田土壤为研究对象，采用Illumina高通量测序技术分析土壤细菌和真菌群落结构的变化，并探讨土壤理化性质和微生物群落间的相关性。结果表明：1）稻鳖共作模式使土壤有机质（Soil Organic Matter，SOM）、总钾（Total potassium，TK）、碱解氮（Alkali-hydrolyzale Nitrogen，AN）、有效磷（Available Phosphorus，AP）和速效钾（Available potassium，AK）含量显著提高了37.72%、15.15%、13.80%、37.37%和21.57%（P<0.05）。2）稻鳖共作模式提高了土壤微生物丰富度和多样性，改变了微生物群落结构。共作使土壤细菌变形菌门（Proteobacteria）、酸杆菌门（Acidobacteriota）、真菌子囊菌门（Ascomycota）和罗兹菌门（Rozellomycota）相对丰度分别增加了6.42%、1.16%、0.44%和2.96%，真菌担子菌门（Basidiomycota）相对丰度降低了0.22%。3）共线网络分析表明，稻鳖共作增加了细菌微生物网络总节点数、边数、平均聚类数和模块化，增强了微生物网络复杂度，加强了群落间的联系；共作降低了真菌微生物网络节点数，但增加了正相互作用的微生物，增强了微生物间的协同合作。4）冗余分析（Redundancy Analysis，RDA）表明，土壤有机质、全钾和速效钾含量是影响细菌群落结构变化的主要环境因子，全钾、速效钾和有效磷含量是影响真菌群落结构变化的主要环境因子。综上，稻鳖共作有利于提高稻田土壤肥力，改变土壤微生物群落结构，并提高了微生物多样性，使微生物群落间的联系更紧密。该研究为探究科学合理的稻田栽培模式提供了重要的科学依据。

Response characteristics of soil microbial communities in paddy fields to rice-turtle integrated system

Abstract: Rice-turtle integrated system refers to a green and efficient ecological breeding technology in which turtles co-exist with rice in rice fields. In this system, turtles use field pests and weeds as food, and rice absorbs and utilizes its residues and excrement as organic fertilizer, which is a modern ecological breeding technology. Soil microorganisms play a vital role in maintaining biodiversity, providing ecosystem functions and enabling nutrient cycling in agroecosystems. However, there are few studies on the effects of rice-turtle co-cropping on soil microbial community structure and functional characteristics and its driving factors. In this study, Illumina high-throughput sequencing technology was used to analyze the response of soil bacterial and fungal community structure and diversity to the rice cultivation system. The correlation between soil physical and chemical properties and microbial community structure was further analyzed. The results showed that: 1) Rice-turtle integrated system was beneficial to increase soil nutrient contents and improve soil fertility. Compared with the rice monoculture system(RM), the contents of soil organic matter (SOM), total potassium (TK), alkali-hydrolyzed nitrogen (AN), available phosphorus (AP) and available potassium (AK) in soil were significantly increased by 37.72%, 15.15%, 13.80%, 37.37% and 21.57% under rice-turtle integrated system (P<0.05). 2) Rice-turtle integrated system could increase soil microbial richness and diversity, and changed the microbial community structure. The ACE index, Chao1 index, Simpson index and Shannon index of soil bacterial community increased by 2.53%, 1.98%, 1.01% and 1.76%, respectively. And the ACE index, Chao1 index and Shannon index of fungal community increased by 7.70%, 7.90% and 4.89%, respectively. At the same time, the relative abundance of Proteobacteria, Acidobacteriota, Chloroflexi, Ascomycota and Rozellomycota increased by 6.42%, 1.16%, 1.79%, 0.44% and 2.96%, respectively. And the abundance of Desulfobacterota, Crenarchaeota, Basidiomycota, Chytridiomycota and Mortierellomycota decreased by 3.68%, 6.46%, 0.22%, 2.52% and 1.26%. 3) Microbial molecular ecological networks can intuitively demonstrate the complex ecological interactions among microorganisms and their responses to environmental changes. Various parameters of microbial networks, such as topological structure, modularity and network composition, can better reflect the relationship between microbial community and its related niche functions. In this study, the network analysis showed that co-cropping increased the total number of nodes, the number of edges, the average clustering number and the modularity of bacterial microbial network, enhanced the complexity of microbial network, and strengthened the relationship between communities. At the same time, co-cropping decreased the number of nodes in fungal microbial network, but increased the number of edges and positive interacting microorganisms, which enhanced the collaboration among microorganisms. 4) Redundancy analysis showed that different soil physical and chemical properties had different effects on the dominant genera of microbial communities. The content of soil organic matter (SOM), total potassium (TK) and available potassium (AK) were the main environmental factors affecting the changes of bacterial community structure, while total potassium (TK), available potassium (AK) and available phosphorus (AP) contents were the main environmental factors affecting the changes of fungi community structure. In conclusion, rice-turtle integrated is beneficial to improving soil fertility, changing soil microbial community structure, enhancing microbial diversity, and making the relationship between microbial communities closer. This study provides an important scientific basis for exploring scientific and reasonable paddy field cultivation mode.