【作者】 蔚霞； 付庆灵； 胡红青； 刘继鹏；

【Author】 Yu Xia.Fu Qingling,Hu Hongqing,Liu Jipeng (College of Resource and Environment,Huazhong Agricultural University,Wuhan 430070,China)

【机构】 华中农业大学资源与环境学院；

【摘要】 本文以两种转Bt水稻（华1517A/09HNZ010和华1517A/09HNZ011）和两种常规水稻（金优207和华1517A/09HNZ009）为供试材料,研究了在淹水条件下秸秆还田后对土壤理化性质、反硝化酶、反硝化速率和土壤微生物功能多样性的影响,从而为转Bt作物对土壤环境的生态风险评价提供参考。其主要研究结果如下:1.秸秆降解中还田后土壤Bt蛋白的降解残留动态分为3个阶段:前期（1～4d）Bt蛋白大量释放、中期（4～30d）快速降解和后期（30～60d）缓慢降解。土壤Bt蛋白达到最大值（4～60d）后（4～60d）的残留动态符合一级动力学和移动指数模型,一级动力学拟合结果中,DT50值在24.47～28.21d之间,DT90值在80.13～94.07d之间,移动对数模型拟合结果中,DT50值在18.88～25.88d之间,DT90值在108.7～267.3d之间。2.与常规水稻相比,转Bt水稻秸秆还田后对土壤全氮、有机质、C/N、NO3-和NH4+养分含量并无明显差异。3.与常规水稻相比,转Bt水稻秸秆还田后对硝酸还原酶和亚硝酸还原酶活性并无影响。常规水稻秸秆还田后土壤硝酸还原酶活性为2.02～11.3NO₃^-～mg/g,转Bt水稻秸秆还田后土壤硝酸还原酶活性为1.72～9.36NO₃^-mg/g。亚硝酸还原酶活性1d时最大,随后急剧下降并无交化,常规水稻处理中保持在0.27～1.39 NO₂^-mg/g,转Bt水稻保持在0.33～1.10 NO₂^-mg/g之间。4.秸秆还田能够降低土壤反硝化速率,且转Bt基因水稻秸秆还田后土壤反硝化速率要小于常规水稻。Bt蛋白对土壤反硝化速率的影响较小,其并不是土壤反硝化的主要影响因素。SPSS多元线性回归分析表明,各个指标对反硝化速率影响程度为:有机质>全氮>C/N>NH₄⁺>NO₃^->Bt蛋白>硝酸还原酶>亚硝酸还原酶。5.BiologEco微平板法表明:转Bt水稻秸秆还田后能够提高微生物的代谢活性,提高对糖类和胺类的利用能力,而对氨基酸、羧酸、聚合物和双亲化合物的利用并无影响;转Bt水稻秸秆还田后物种的丰富度指数、优势度指数和McIntosh指数均大于常规水稻,而均匀度指数小于常规水稻;转Bt水稻和常规水稻秸秆还田后土壤微生物对碳源的利用方式存在显著性差异。聚类分析结果表明,微生物生长的对数期,常规水稻和转Bt水稻秸秆还田后对碳源的利用差异显著,到达稳定期后差异不再显著。更多还原

【Abstract】 In this experiment,transgenic Bt rice（HUA 1517A/09HNZ010 and HUA 1517A/09HNZ011） and non-transgenic rice（JIN YOU 207 and HUA 1517A/09HNZ009） were used as materials to investigate the effect of rice straws that were returned to field in flooded conditions on soil physico-chemical properties, denitrifying enzyme,denitrifying rate and microbial diversity,so as to provide a scientific basis for ecological risk assessment of transgenic Bt crops.The main results and conclusions were as follows: 1.After straws were returned to field,the residual Bt protein in soil showed 3 dynamic stages:early releasing stage（1～4 days）,rapidly declining stage（4～30 days） and last stable stage（30～60 days）.Both the first-order kinetic model and shift-log model fitted the dynamics of residual Bt protein in the highest content （4～60 days）.According to calculation,DT50 and DT90 in the first-order kinetic model were within the ranges of 24.47～28.21d and 80.13～94.07d respectively,while the corresponding days of DT50 and DT90 in shift-log model were 18.88～25.88d and 108.7～267.3d. 2.Compared with non-transgenic Bt rice,transgenic Bt rice straws in paddy soil did not have much differences in the content of the organic matter,total nitrogen,C/N,NO₃^- and NH₄⁺. 3.Compared with non-transgenic Bt rice,transgenic Bt rice straws in paddy soil had no significant effect on the activities of nitrate reductase and nitrite reductase.After non-transgenic Bt rice straws were returned to field, the calculated activity of soil nitrate reductase was within the ranges of 1.72-9.36 N03- mg/g;for transgenic Bt rice straws,the activity was 2.02～11.3 NO₃～rng/g.The activities of nitrite reductase reached the maximum on the 1st day,and then dropped dramatically.The calculated activities of nitrate reductase were within the ranges of 0.33～1.10 NO₂^-mg/g and 0.27～1.39 NO₂^-mg/g in the corresponding treatments of transgenic Bt rice straws and non-transgenic Bt rice straws. 4.The denitrifying rate can be decreased by returning straws,which shows a higher rate in the treatments of transgenic Bt rice straws than non-transgenic Bt rice straws.Bt protein was not the main influential factor on soil denitrifying rate since it had less effect on soil denitrifying rate.The affection degree of each index obtained by SPSS multiple linear regression is displayed as follows:Organic matter > Total nitrogen > C/N > NH₄⁺> NO₃^-> Bt protein > Nitrate reductase activities > Nitrite reductase activities. 5.The results from Biolog Eco micro flat method showed that the microbial metabolic activity and the ability of using carbohydrate and amine can be improved by returning transgenic Bt rice straws to field,while it had no effect on the using of carboxylic acids,amino acids,polymer and phenols.After rice straws returning,the Shannon index,Simpsons dominance index and Mcintosh index of soil species all were greater in transgenic Bt paddy soil than those in contrast treatment,while the evenness index was just the opposite.The use pattem of carbon source by soil microorganism had significant differences between transgenic Bt rice and non-transgenic Bt rice after rice straws returning.The cluster analysis indicated that there were significant differences between the two tested rices in the use pattern of carbon source at exponential stage after straws returning,while it was no longer significant in the stable stage.更多还原