中文摘要：

摘要：采用土壤盆栽试验法研究了cd、低于国家“土壤环境质量标准”规定的Ⅱ类土壤环境基准值300mg／kg干土时的Ph与cd复合处理对冬小麦幼苗根系分泌物总酚酸和简单糖类及其与根际土壤微生物活性关系的影响特征。结果表明：1）冬小麦幼苗生长3周时，随cd浓度的升高，根系简单糖类的分泌量表现为降低一增加一降低现象，而酚酸分泌量主要表现为显著（P〈O．05）增加；幼苗生长7周时，简单糖类分泌量极显著（P〈O．01）降低，酚酸分泌量表现为降低一增加一降低现象；幼苗生长12周时，简单糖类分泌量在cd≤50．00mg/kg干土时降低，cd浓度为70．00mg／kg干土时极显著（P〈O．01）增加，酚酸分泌量在Cd≤20．00mg／kg干土时降低，Cd〉20．00mg／kg干土时增加。2）低于国家“土壤环境质量标准（GBl5618--1995）”规定的Ⅱ类土壤环境基准值（300ms／kg）时，Pb的存在会对cd胁迫下冬小麦根系酚酸和简单糖类分泌特征有明显影响，主要表现为可使cd处理下幼苗根系酚酸分泌量增加，而简单糖类分泌量降低。3）低Pb／Cd处理与cd处理之间，冬小麦幼苗根系酚酸和简单糖类分泌量与细菌、真菌和放线菌数量、脲酶、转化酶和脱氢酶活性、有机质和全氮含量、微生物量碳等根际土壤微生物生化活性之间的相关性特点明显不同。

英文摘要：

Abstract： The study explored the effects of Cd and the combined pollution of the low dose of Pb （ 〈 300 mg/kg dry weight soil） and Cd on the content of phenolic acid and simple glucides exudating from winter wheat seedlings root and the relationship between them and rhizosphere soil microbial activity. Five levels of Cd, five levels of the combined pollution of Pb and Cd, and the control without the addition of heavy metal （0.00 mg/kg dry weight soil） were selected to examine the response of them through pots experiments at the third, seventh, and twelfth weeks after seedlings emerged. The result indicated that ： 1 ） Compared to the control, the content of simple glucides decreased-increased-decreased and it of phenolic acid significantly （P 〈 0. 05 ） increased when wheat seedlings had grown for three weeks with the increase of Cd concentration. And the content of simple glucicdes significantly （ P〈0.01 ） decreased and it of phenolic acid decreased- increased-decreased at the seventh week. The content of simple glucides decreased at Cd ≤50.00 mg/kg dry soil and significantly （ P〈0.01 ） increased at 70.0 mg/kg dry soil Cd. However, phenolic acid content decreased at Cd ≤ 20.00mg/kg dry soil and increased at Cd〉20.00 mg/kg dry soil. 2） Low doses of Pb2（ 〈 300 mg/kg） significantly affected the response character of simple glucides and phenolic acid contents to the stress of Cd. Furthermore, it mainly exihibited that the phenolic acid content increased and simple glucides content decreased under the stress of Pb/Cd. 3 ） Between Pb/Cd and Cd, the correlation character was different between contents of simple glucides and phenolic acid and rhisophere soil microbial activities such as the number of soil bacterial, fungi, and actinomycetes, soil urease, invertase, and dehydrogenase activities, the content of soil organic matter and total nitrigen, and soil microbial biomass carbon.