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为正确评价重金属污染下冬小麦根际土壤微生态系统的安全性和稳定性,采用盆栽试验法研究了铅(Pb)含量低于国家“土壤环境质量标准(GB 15618-1995)”规定的Ⅱ类土壤环境基准值(350.00 mg/kg,干土)时,与镉(Cd)复合处理对冬小麦幼苗根际土壤氧化还原酶活性、肥力指数(Biological index of fertility,BIF)及碳/氮(C/N)的影响.结果表明:(1)幼苗生长3周时,Cd处理下过氧化氢酶和多酚氧化酶活性显著(P<0.05)增加,脱氢酶活性显著(P<0.05)降低;7周时多酚氧化酶和过氧化氢酶活性显著(P<0.05)降低;12周时,多酚氧化酶和脱氢酶活性显著(P<0.05)降低.此外,根际土壤生物学肥力指标BIF值主要表现为降低,而根际土壤C/N值在幼苗生长3周和12周时显著(P<0.05)降低,7周时却极显著(P<0.01)升高.(2)低含量Pb与Cd对脱氢酶和过氧化氢酶活性、BIF值主要起协同抑制效应,对多酚氧化酶活性表现出拮抗效应.幼苗生长3周和12周时,低含量Pb可减轻Cd对C/N值的降低效应,7周时,低含量Pb和Cd协同促进C/N值升高.土壤Pb含量低于国家“土壤环境质量标准”规定的Ⅱ类土壤环境基准值时,仍会明显影响Cd污染下冬小麦幼苗根际土壤的生化功能特征.
In order to correctly evaluate the safety and stability of winter wheat rhizosphere soil microbial ecosystem under heavy metal pollution, the pot experiment was conducted to study the effect of lead (Pb) content below the national standard of soil environmental quality (GB 15618-1995) The soil rhizosphere soil enzyme activity, BIF and C / N ratio in winter wheat seedlings were treated with Cd (Cd) The results showed that: (1) At 3 weeks of seedling growth, the activity of catalase and polyphenol oxidase increased remarkably (P <0.05) and the activity of dehydrogenase was significant (P <0.05) (P <0.05) decreased significantly at 7th week, while the activity of polyphenol oxidase and dehydrogenase decreased significantly at 12th week (P <0.05) .In addition, the activities of rhizosphere soil microbes The BIF value of fertility index was mainly decreased, while the rhizosphere soil C / N value decreased significantly (P <0.05) at 3 weeks and 12 weeks of seedling growth, but increased significantly at 7 weeks (P <0.01). 2) Low content of Pb and Cd had synergistic inhibitory effect on the activity of dehydrogenase, catalase and BIF, and showed antagonistic effect on polyphenol oxidase activity. At 12 weeks, the low Pb content reduced the effect of Cd on the C / N value, and at the 7th week, the low Pb and Cd content promoted the increase of C / N value.The content of Pb in soil was lower than the National Soil Environmental Quality Standard ", The biochemical function of rhizosphere soil of winter wheat seedlings under Cd pollution will still be significantly affected.