乙草胺及铜离子复合施用对黑土农田生态系统土著微生物的急性毒性效应

采用实验室模拟方法研究了乙草胺、铜离子及其复合物在施加12d内对黑土农田生态系统中土著微生物种群数量及其土壤生物学特性的急性毒性效应。结果表明：单独施加乙草胺或铜离子对土壤中主要微生物类群——细菌、放线菌以及作物生长有益微生物类群——自生固氮菌、矿化磷细菌及硅酸盐细菌具有明显的急性毒性作用；这种毒性效应尤以第6d最为显著。单独施加乙草胺或铜离子可使供试土壤中的真菌数量明显提高，第9d时，乙草胺和铜离子处理土壤中真菌数量比对照分别提高20．87倍和3．01倍。乙草胺和铜离子的复合施加在前6d对土壤中所有被检测微生物种群的毒性均比其相应的单因子的毒性强，表现出明显的乙草胺—铜离子协同毒性效应。乙草胺对供试土壤的呼吸强度和脱氢酶活性具有明显的刺激效应。铜离子在前6d刺激供试土壤呼吸强度增强，从第9d开始抑制供试土壤的呼吸强度；而铜离子在处理过程中对土壤脱氢酶活性却表现为强烈的抑制效应。当乙草胺和铜离子复合施加时，对供试土壤的呼吸强度和脱氢酶活性的作用随作用时间呈现不同作用规律。

Combined Effects of Acute Toxicity of Acetochlor and Copper on Soil Microbial Population and Biological Characteristics in Maize - Wheat - Soybean Agroecosystem

The combined effects of acute toxic ity of acetochlor and copper of some s oil indigenous microbial populatio n in term of colony forming units /g(CFU)and soil biological characteristic s in a maize -wheat -soybean agroecosystem were studied in labo-ratory.The results showed that toxicity of acetochlor and copper on soil bacteria,actinomyces and three pla nt -growth -benefits bacteria,including N -fixing bacte ria,P -mineralization bacteria and K -mineralization bacteria,were en hanced when used by both comporison with the control of s ingle.It has been indicated that ace tochlor and copper stimulated growt h of soil fungi when they were applied by single.However,when used by joint,they inhibited the growth of fungi.Acetochlor can promote soil short -term -induced respiration(SIR)and dehydrogenase activity.Copper inhibitat dehydrogenase activity a during whole treatment;and in-hibitated the soil short -term -induced respiration after the sixth days.It was suggested that joint of aceto chlor and copper have different effects on the soil SIR and dehydrogenase with different treatment time.