不同供磷水平对柳枝稷根际土壤有机酸、无机磷及微生物的影响

Effects of different phosphorus supply levels on the organic acids,inorganic phosphorus,and microorganisms in the rhizosphere soil of switchgrass(Panicum virgatum L.)

本研究旨在探索不同供磷水平对根际土壤有机酸、无机磷和微生物群落的影响,挖掘根际土壤微生态特征,对促进土壤磷素循环具有重要意义。本试验采用随机区组试验设计,以柳枝稷‘Alamo’和‘Pathfinder’品种为材料,设置3个磷水平:P0(0 kg∙hm^(-2))、P30(30 kg∙hm^(-2))和P90(90 kg∙hm^(-2)),研究不同磷水平下柳枝稷根际土壤有机酸组成及含量、无机磷形态及含量以及微生物种群落多样性。研究结果表明,施磷水平对根际土壤有机酸、无机磷含量和微生物群落有显著影响。与P0相比,不同施磷水平下‘Alamo’品种的根际土壤有机酸含量增幅更大,无机磷含量更高。而在微生物群落方面,‘Alamo’和‘Pathfinder’品种呈现相似的变化规律。在P30和P90处理下,根际土壤中琥珀酸、苹果酸、马来酸和丙二酸含量显著增加,辛二酸含量降低。此外,施磷后根际土壤中的Ca_(2)-P、Al-P、Fe-P、O-P和Ca_(10)-P含量均显著增加。细菌群落的Chao1指数、ACE指数、Shannon指数和Simpson指数在施磷后也显著增加,而物种组成在门水平上以变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)和绿弯菌门(Chloroflexi)为优势菌门。综合分析发现,不同磷水平下,柳枝稷根际土壤中的有机酸与无机磷间关系不显著。细菌群落的丰富度和多样性受有机酸和无机磷的共同影响,不同优势菌门与有机酸和无机磷的关系具有差异性。综上所述,有机酸—无机磷—微生物构成的根际土壤微生态系统是相互协调的系统,对磷资源的高效利用具有积极作用。

This study aimed to explore the effects of different phosphorus supply levels on soil organic acids and inorganic phosphorus contents,and microbial communities,as well as to investigate the microbial ecological characteristics in the rhizosphere.The results are important for promoting soil phosphorus cycling.The experiment employed a randomized block design with‘Alamo’and‘Pathfinder’varieties of Panicum virgatum L.Three phosphorus levels were set:P0(0 kg·hm^(-2)),P30(30 kg·hm^(-2)),and P90(90 kg·hm^(-2)),to study the composition and content of rhizosphere soil organic acids,inorganic phosphorus,and microbial population diversity.The results showed that phosphorus levels had a significant impact on rhizosphere soil organic acids and inorganic phosphorus contents,and microbial communities.At two phosphorus application levels,the‘Alamo’variety exhibited a greater increase in rhizosphere soil organic acid content and higher levels of rhizosphere soil inorganic phosphorus,compared with P0 treatment.In terms of microbial communities,both‘Alamo’and‘Pathfinder’varieties showed similar patterns of change.Under the P30 and P90 treatments,the succinic,malic,maleic,and malonic acid contents in the rhizosphere soil significantly increased,whereas the suberic acid content decreased.Additionally,the contents of Ca_(2)-P,Al-P,Fe-P,O-P,and Ca_(10)-P in the rhizosphere soil significantly increased after phosphorus application.Furthermore,the Chao1,ACE,Shannon,and Simpson indices of the bacterial communities significantly increased after phosphorus application,with the phyla Proteobacteria,Bacteroidetes,Actinobacteria,and Chloroflexi dominating at the phylum level.The comprehensive analysis found that under different phosphorus levels,the relationship between organic acids and inorganic phosphorus was not significant.The abundance and diversity of bacterial communities were jointly influenced by organic acids and inorganic phosphorus,and the relationships between the dominant bacterial phyla,organic acids,and inorganic phosphorus varied.In conclusion,the rhizosphere soil microecosystem,composed of organic acids,inorganic phosphorus,and microorganisms were a harmonious system that played a positive role in the efficient utilization of phosphorus resources.