运用多隔层根箱研究玉米幼苗根际微域中芘的降解

Degradation of Pyrene in Rhizosphere of Maize Seedlings (Zea mays L.) in a Rhizobox

采用多隔层根箱,通过尼龙撩网插片的控制,实现根室土(S0)、离根室0～2mm(S1)、2～4mm(S2)、4～6mm(S3)及>6mm(S4)各室层土壤的分离采集,分析离根系表面不同距离土壤芘的根际降解,并借助脂肪酸甲酯(fattyacidmethylester,FAME)分析土壤微生物群落结构的空间响应机制。结果表明:种植玉米处理的各室层内土壤可提取态芘含量存在显著的不同,其大小顺序为S4>S3>S0>S2>S1;各室层微生物群落结构存在显著的变化,其中微生物生物量和丛枝菌根真菌特征脂肪酸含量表现出与土壤可提取态芘含量变化相反的变化趋势。未种植玉米处理的各室层土壤可提取态芘含量和微生物群落结构没有差异。土壤可提取态芘含量与微生物生物量和丛枝菌根真菌的特征脂肪酸呈显著负相关(p<0.01)。

An investigation was conducted by using fatty acid methyl ester （FAME） profiles to follow the spatial response of the microbial community at 2 mm scale with the purpose of illustrating the mechanism of nonlinear spatial dependence of pyrene degradation on the distance from the root surface in the rhizosphere of maize seedlings （Zea mays L.）, The soil in the rhizobox was divided into several compartments separated by nylon meshes, Soil samples were collected from the root compartment （SO） and other compartments of 0-2 mm （S1）, 2-4 mm （S2）, 4-6 mm （$3）, 〉 6 mm （S4） far from the root compartment to determine extractable pyrene concentrations and fatty acid methyl ester. Zea mays L. was grown in environmental chambers for 45 days with soil spiked with 600 mg/kg pyrene. The results showed that significant differenc6s existed between the compartments in extractable pyrene concentrations in treatments with maize, following the order of S4〉S3〉S0〉S2〉S1. However, an opposite trend in variation existed with fatty acid indicators of soil microbial biomass and of arbuscular mycorrhizal fungi （AMF）. Significant differences existed among the compartments in microbial community structure in treatments with maize. No difference existed in extractable pyrene concentration and microbial community structure between treatments without maize. Significantly negative correlations （p〈0.01） existed between the extractable pyrene concentrations and fatty acid indicators for microbial biomass and fatty acid indicators for AMF in various sampling zones of soils with growth of maize.