乙草胺对土壤脲酶动力学特征的影响

Effects of acetochlor on soil urease kinetic characteristics

采用室内模拟试验方法,以典型棕壤为供试土壤,研究不同浓度乙草胺对土壤脲酶活性和酶动力学参数的影响。结果表明,不同浓度乙草胺能显著抑制土壤脲酶活性,并在培养的第3～6 d达到最大抑制;利用模型y=c/(1+bx)和y=c(1+ax)/(1+bx)对不同浓度乙草胺与土壤酶活性的关系进行拟合,证明模型y=c/(1+bx)拟合效果较好,表明乙草胺除草剂对土壤脲酶的抑制作用为完全抑制,而脲酶ED50为13.12～75.76 mg/kg;乙草胺的施入使土壤脲酶Vmax值降低,Km值则保持不变,属于典型的非竞争性抑制。

Effects of different contents of acetochlor on soil urease and its kinetic characteristics in brown soil were study in incubation days with indoor experiments.The results show that soil urease activities are obviously inhibited by different contents of acetochlor,and the peak inhibition ratios are from the third incubation day to the sixth incubation day.Two models,y=c/（1＋bx） and y=c（1＋ax）/（1＋bx）,were used to describe the effect type of acetochlor on soil urease,the fitted results show that the model,y=c/（1＋bx） is more suitable,and this means the inhibition is a completely inhibition.The ED50 values calculated from the model are from 13.12 to 75.76 mg/kg.The soil urease Km is not obviously effected by acetochlor,and the Vmax becomes small.This kind of the effect belongs to the non-competitiveness inhibition.