Cadmium contamination inevitably affects the microbially mediated transformation of nitrogen in soils with wheat straw return. The responses of nitrogen functional microorganisms to cadmium in acidic and alkaline soils under wheat straw returned are still unclear. In this study, quantitative polymerase chain reaction (qPCR) and sequencing of nitrifying and denitrifying bacteria were performed to investigate the effects of wheat straw application on nitrogen conversion in different Cd-contaminated soils during an incubation experiment. Results showed that the presence of Cd decreased the abundance of gene catalyzing nitrification and gene catalyzing denitrification process, resulting the accumulation of NH-N and reduction of NO-N in the acidic soils. Additionally, Cd-contamination stimulates the nitrification catalyzed by bacterial gene and thus reduced the NH-N content in the alkaline soils. Meanwhile, Cd dominated the decrease of NO-N content by promoting denitrification process catalyzed by gene. Among all nitrifying and denitrifying microorganisms, are tolerant to Cd stress under alkaline condition but sensitive to acidic condition, which dominantly harbored gene in the acidic soils and bacterial gene in the alkaline soils. This study aimed to provide reasonable information for the rational adoption of wheat straw returning strategies to realize nitrogen regulation in Cd-contaminated farmland soil.

中文翻译：

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麦秆还田不同镉污染土壤土壤微生物氮循环策略


镉污染不可避免地影响麦秆还田土壤中微生物介导的氮转化。麦秆还田酸性和碱性土壤中氮功能微生物对镉的响应尚不清楚。本研究通过定量聚合酶链式反应（qPCR）和硝化反硝化细菌测序，研究了孵化实验中小麦秸秆施用对不同镉污染土壤氮转化的影响。结果表明，Cd的存在降低了酸性土壤中硝化催化基因和反硝化基因催化丰度，导致NH-N积累和NO-N减少。此外，镉污染刺激细菌基因催化的硝化作用，从而降低碱性土壤中的NH-N含量。同时，Cd通过促进基因催化的反硝化过程，主导NO-N含量的降低。在所有硝化和反硝化微生物中，在碱性条件下能耐受Cd胁迫，但对酸性条件敏感，其在酸性土壤中占优势基因，在碱性土壤中占优势细菌基因。本研究旨在为合理采用麦秆还田策略实现镉污染农田土壤氮素调控提供合理依据。