封冻前灌水对‘富士’苹果根际细菌群落及速效养分的影响

Effects of Irrigation Before Soil Freezing on Bacterial Community Composition and Available Nutrient Content in‘Fuji’Apple Rhizosphere

以5年生‘富士’苹果树为试验材料,在土壤封冻前充分灌溉,于次年1月与4月取样分析根际土壤细菌群落组成结构及速效养分含量的变化。结果显示,封冻前灌水在提高土壤含水量、稳定土壤温度的同时,显著提高土壤速效养分含量,降低土壤有机质含量,增加根际土壤细菌群落的丰富度和多样性,降低土层之间及冬春季之间细菌群落的差异性。其中,土壤有效氮、磷、钾含量分别提高了15.83%、21.13%和8.22%,有机质含量降低了19.86%。此外,初春时期果树根系密度、根系活力和根系氮含量分别提升了10.3%、15.6%和13.3%。功能基因定量分析显示,封冻前灌水可以显著增加土壤细菌和真菌数量,包括氨氧化古菌、固氮菌和反硝化菌在内的氮功能菌群丰度分别提高了35.18%、18.12%和19.53%,增强土壤硝化与反硝化作用。

In this study,the 5-year-old‘Fuji’apple trees were used as materials.After full irrigation before soil freezing,samples were taken in the next January and April to analyze the changes of bacterial community composition and available nutrients in rhizosphere soil.The results showed that irrigation before freezing not only increased soil moisture status and stabilized soil temperature,but also significantly increased soil available nutrient content,and reduced soil organic matter content.The content of soil available nitrogen,phosphorus and potassium increased by 15.83%,21.13%and 8.22%,while the content of organic matter decreased by 19.86%.In addition,the root density,root activity and root nitrogen content increased by 10.3%,15.6%and 13.3%,respectively in early spring.Quantitative PCR analysis of functional genes showed that the irrigation before soil freezing significantly increased the number of soil bacteria and fungi,including ammonia-oxidizing archaea(AOA),nitrogen fixing bacteria and denitrification bacteria abundance increased 35.18%,18.12%and 19.53%,respectively,thus promoting soil nitrification and denitrification.