【作者】 何丹；

【导师】 戴中民；

【作者基本信息】 浙江大学 ， 土壤学， 2025， 硕士

【摘要】 土壤磷(P)是植物生长发育必需的大量营养元素,并参与土壤重要的生物地球化学循环过程。土壤解磷微生物通过分泌H~+、有机酸等将难溶性的无机磷溶解或分泌磷酸酶等物质将有机磷矿化,释放有效磷。解磷微生物的碳源、磷源及其本身对磷素转化过程具有重要的作用。有机碳为微生物提供能量来源,有机磷是潜在有效磷的重要储备,而解磷微生物是土壤磷素转化过程的主要驱动力。通过输入有机碳、有机磷和解磷菌剂,能够调控土壤微生物活性和磷转化路径,但当前研究主要侧重在有机碳、有机磷和解磷菌剂种类和添加量的影响规律,有机碳、有机磷、解磷菌的多样性(不同种类的数量)如何影响土壤磷素有效性和微生物群落的研究鲜有报道。本研究选取全国20种土壤开展室内培养实验,探究有机碳、有机磷和解磷菌多样性梯度对土壤磷素有效性和解磷酶活性的影响,揭示磷转化相关功能基因(phoD、phoC、bpp、pqqC等)丰度和微生物群落的响应特征。有机碳多样性梯度为不同有机碳的数量组合,有机磷多样性梯度为不同有机磷的数量组合;解磷菌多样性梯度为不同解磷菌株的数量组合。主要研究结果如下:(1)研究设置0种、1种、2种、4种、8种共四个梯度的碳源多样性处理,通过室内培养探讨了碳源多样性对土壤磷素有效性、解磷酶活性和微生物群落的作用机制。结果表明,添加1-8种有机碳后土壤有效磷含量未呈现显著变化,但土壤核酸酶和植酸酶活性随有机碳多样性的增加显著上升。与对照相比,微生物phoC(编码酸性磷酸酶)、bpp(编码植酸酶)和pqqC(无机磷溶解)基因的丰度在添加8种有机碳的处理后显著增加了290%、155%和63.3%,同时微生物多样性下降。随着有机碳多样性的增加,微生物互作网络改变,网络变得更加模块化,网络中的关键节点微生物种类和数量逐渐增加。同时,碳源多样性还改变了特异性微生物的碳源响应特征,与对照相比,在8种碳源组合的处理下,敏感型微生物物种的上调和下调物种数量分别增加了31和45个,其中厚壁菌门(Firmicutes)和放线菌门(Actinobacteriota)微生物是对碳源多样性最为敏感的微生物物种。(2)研究设置0种、1种、2种、4种、8种共四个梯度的有机磷源多样性处理,通过室内培养探讨了磷源多样性对土壤磷素有效性、解磷酶活性和微生物群落的作用机制。结果表明,随着有机磷源多样性增加,土壤有效磷含量(从对照组的39.0 mg/kg增至8种有机磷处理的411 mg/kg)和植酸酶活性(从未添加有机磷:1.29 U/g增至添加8种有机磷的12.4 U/g)显著提升。与对照相比,添加4种和8种有机磷处理酸性磷酸酶活性显著增加61.0%和67.8%,添加8种有机磷处理基因pqqC的丰度显著增加了1.3×10~8 copies/g。与对照相比,放线菌门和厚壁菌门的丰度在添加8种有机磷的处理后增加了17.0%和19.5%,同时微生物多样性发生下降。随着有机磷多样性的增加,微生物互作网络结构发生改变,微生物竞争加剧。在添加8种有机磷处理中,放线菌门以其高丰度、网络枢纽地位及与植酸酶的强相关性,成为提升土壤磷素有效性的关键微生物类群。(3)研究设置0种、1种、2种、4种、8种共四个梯度的解磷菌多样性处理,通过室内培养探讨了解磷菌多样性对土壤磷素有效性、解磷酶活性和微生物群落的作用机制。本研究揭示,与对照相比,土壤有效磷含量、酸性磷酸酶活性、碱性磷酸酶活性、植酸酶活性和基因phoC的丰度在添加8种解磷菌的处理后显著增加了35.9%、42.3%、25.4%、84.62%和189.3%,变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)的丰度增加了52.3%和76.8%。添加解磷菌对微生物多样性没有显著改变。随着解磷菌多样性的增加,微生物网络复杂度下降,互作关系简化,但添加8种解磷菌时微生物共现网络的关键节点数较对照组增加了83个。与对照组相比,添加8种解磷菌处理敏感型微生物物种的上调和下调物种数量分别增加了85和27个,使得更多元的微生物类群参与到群落调控中。本研究系统解析了有机碳、有机磷和解磷菌多样性对土壤磷循环的调控机制。发现有机碳多样性通过影响phoC、bpp和pqqC基因丰度与酶活性,影响微生物的解磷潜能;有机磷多样性直接提高土壤磷素有效性,并驱动关键菌群成为磷循环核心参与者;解磷菌多样性输入直接提高土壤磷素有效性,增强解磷酶活性,微生物通过功能冗余与关键物种协同作用维持磷循环稳态。本研究突破传统单一要素研究局限,为深入理解土壤磷素转化机制、优化农业生态系统磷素管理策略提供了全新理论依据与实践方向。更多还原

【Abstract】 As a key indispensable nutrient for plants,soil phosphorus(P)plays a vital role in their growth and developmental processes and is involved in important biogeochemical cycling processes in soil.Phosphorus-solubilizing microorganisms in soil dissolve insoluble inorganic phosphorus by secreting H~+and organic acids,or mineralize organic phosphorus by secreting substances such as phosphatase to release available phosphorus.The carbon sources,phosphorus sources of phosphorus-solubilizing microorganisms and the microorganisms themselves play important roles in the process of phosphorus transformation.Organic carbon provides an energy source for microorganisms,organic phosphorus is an important reserve of potential available phosphorus,and phosphorus-solubilizing microorganisms are the main driving force for the transformation of soil phosphorus.By adding organic carbon,organic phosphorus and phosphorus-solubilizing bacteria agents,the activity of soil microorganisms and the phosphorus transformation pathway can be regulated.However,current research mainly focuses on the influence trends of the types and addition amounts of organic carbon,organic phosphorus and phosphorus-solubilizing bacteria agents.There are few reports on how the diversity(number of different types)of organic carbon,organic phosphorus and phosphorus-solubilizing bacteria affects soil phosphorus availability and the microbial community.In this study,20 types of soils from across the country were selected to conduct laboratory incubation experiments.The effects of gradients of organic carbon,organic phosphorus,and phosphate-solubilizing bacteria diversity on the availability of soil phosphorus and the activity of phosphatase were explored,and the response characteristics of the abundances of phosphorus transformation-related functional genes(such as phoD,phoC,bpp,pqqC,etc.)and the microbial community were revealed.The gradient of organic carbon diversity refers to the quantitative combinations of different types of organic carbon,the gradient of organic phosphorus diversity refers to the quantitative combinations of different types of organic phosphorus,and the gradient of phosphate-solubilizing bacteria diversity refers to the quantitative combinations of different phosphate-solubilizing bacterial strains.The key results obtained from this study are as follows:(1)In this study,four gradients of carbon source diversity treatments with 0 type,1 type,2 types,4 types and 8 types were set up,and the mechanism of the effects of carbon source diversity on soil phosphorus availability,phosphatase activity and the microbial community was explored through laboratory incubation.The results showed that after adding 1-8 types of organic carbon,there was no significant change in the content of soil available phosphorus,but the activities of soil nuclease and phytase increased significantly with the increase in organic carbon diversity.Compared with the control,the abundances of the genes phoC(encoding acid phosphatase),bpp(encoding phytase)and pqqC(inorganic phosphorus dissolution)increased significantly by 290%,155%and 63.3%after the treatment with 8 types of organic carbon,while the microbial diversity decreased.With the increase in organic carbon diversity,the structure of the microbial interaction network changed,the network became more modular,and the types and numbers of key node microorganisms in the network gradually increased.At the same time,the carbon source diversity also changed the carbon source response characteristics of specific microorganisms.Compared with the control,in the treatment with the combination of 8 carbon sources,the numbers of up-regulated and down-regulated sensitive microbial species increased by 31 and 45 respectively,among which the microorganisms of Firmicutes and Actinobacteriota were the most sensitive microbial species to the carbon source diversity.(2)In this study,four gradients of organic phosphorus source diversity treatments with 0type,1 type,2 types,4 types and 8 types were set up,and the mechanism of the effects of phosphorus source diversity on soil phosphorus availability,phosphatase activity and the microbial community was explored through laboratory incubation.The results showed that with the increase in the diversity of organic phosphorus sources,the content of soil available phosphorus(from 39.0 mg/kg in the control group to 411 mg/kg in the treatment with 8 types of organic phosphorus)and the phytase activity(from 1.29 U/g without adding organic phosphorus to 12.4 U/g in the treatment with 8 types of organic phosphorus)increased significantly.Compared with the control,the activities of acid phosphatase in the treatments with 4 types and 8 types of added organic phosphorus increased significantly by 61.0%and67.8%,and the activity of alkaline phosphatase in the treatment with 2 types of added organic phosphorus increased significantly by 67.8%.Compared with the control,the abundance of the gene pqqC in the treatment with 8 types of added organic phosphorus increased significantly by 1.3×10~8 copies/g.Compared with the control,the abundances of Actinobacteriota and Firmicutes increased by 17.0%and 19.5%,respectively,after the treatment with 8 types of added organic phosphorus,while microbial diversity decrease.With the increase in the diversity of organic phosphorus,the structure of the microbial interaction network changed,and the microbial competition intensified.In the treatment with 8 types of added organic phosphorus,Actinobacteriota,with its high abundance,pivotal position in the network and strong correlation with phytase,became the key microbial group for enhancing soil phosphorus availability.(3)In this study,four gradients of phosphorus-solubilizing bacteria diversity treatments with 0 type,1 type,2 types,4 types and 8 types were set up,and the mechanism of the effects of phosphorus-solubilizing bacteria diversity on soil phosphorus availability,phosphatase activity and the microbial community was explored through laboratory incubation.This study revealed that compared with the control,the content of soil available phosphorus,the activities of acid phosphatase,alkaline phosphatase and phytase,and the abundance of the gene phoC increased significantly by 35.9%,42.3%,25.4%,84.62%and 189.3%after the treatment with8 types of phosphorus-solubilizing bacteria.The abundances of Proteobacteria and Bacteroidetes increased by 52.3%and 76.8%.Adding phosphorus-solubilizing bacteria had no significant change on the microbial diversity.With the increase in the diversity of phosphorus-solubilizing bacteria,the complexity of the microbial network decreased and the interaction relationship was simplified.However,the number of key nodes in the microbial co-occurrence network in the treatment with 8 types of phosphorus-solubilizing bacteria increased by 83 compared with the control group.Compared with the control,the numbers of up-regulated and down-regulated sensitive microbial species in the treatment with 8 types of added phosphorus-solubilizing bacteria increased by 85 and 27 respectively,enabling a more diverse range of microbial groups to participate in community regulation.This study systematically analyzed the regulatory mechanisms of the diversity of organic carbon,organic phosphorus and phosphorus-solubilizing bacteria on the soil phosphorus cycle.It was found that the diversity of organic carbon affects the phosphorus-solubilizing potential of microorganisms by influencing the abundances of the genes phoC,bpp and pqqC and the enzyme activities;the diversity of organic phosphorus directly improves soil phosphorus availability and drives key bacterial groups to become core participants in the phosphorus cycle;the input of the diversity of phosphorus-solubilizing bacteria directly increases soil phosphorus availability and enhances the activity of phosphatase,and microorganisms maintain the stability of the phosphorus cycle through the synergistic action of functional redundancy and key species.This study breaks through the limitations of traditional single-factor research and provides a new theoretical basis and practical direction for a deeper understanding of the mechanism of soil phosphorus transformation and the optimization of phosphorus management strategies in agricultural ecosystems.更多还原