【摘要】 为探究威百亩对土壤反硝化作用的影响及作用机制,采用理化分析和变性梯度凝胶电泳方法分析浓度20、100和500 mg/kg威百亩熏蒸对土壤反硝化作用及nirS型反硝化细菌群落结构的影响。结果显示,威百亩熏蒸处理0、14 d后,500 mg/kg浓度处理的土壤反硝化率为84.64%、90.52%,分别显著低于对照的86.72%和91.87%,100、20 mg/kg浓度处理的土壤反硝化率与对照均无显著差异;熏蒸处理28、56和84 d后,4个处理的土壤反硝化率均无显著差异。与对照相比,3个浓度威百亩熏蒸处理0、14、28、56和84 d后的土壤nirS型反硝化细菌群落的多样性指数和均匀度指数均差异不显著。除56 d外,20 mg/kg浓度熏蒸处理0、14、28和84 d的土壤细菌群落丰富度指数分别为8.77、14.77、9.77和8.75,均显著低于对照;100 mg/kg浓度熏蒸处理0、14和28 d后的土壤细菌群落丰富度指数分别为10.76、6.77和10.78,显著低于对照,而处理56、84 d后,土壤细菌群落丰富度指数与对照无显著差异。500 mg/kg浓度威百亩熏蒸处理后,土壤反硝化作用在熏蒸后0～14 d受到抑制,28 d后土壤反硝化作用自然恢复;土壤细菌群落丰富度指数无论熏蒸初期或后期与均对照差异不显著。威百亩对土壤反硝化强度的影响与nirS型硝化细菌群落结构变化无关,说明nirS型反硝化细菌在土壤反硝化作用中不起主要作用。更多还原

【Abstract】 To explore the impact and mechanism of soil fumigants on soil denitrification, physicochemical analysis and denaturing gradient gel electrophoresis(DGGE) were performed to investigate the effects of fumigant metham-sodium with different doses at 20, 100 and 500 mg/kg on soil denitrification and the structure of nirS bacteria community. The results showed that at 0 d and 14 d after the methamsodium fumigation treatment, soil denitrification rate with the 500 mg/kg treatment was 84.64% and90.52%, respectively, significantly lower than those of the control group(86.72% and 91.87%). Compared with the control group, soil denitrification rate with the 100 and 20 mg/kg treatment was not significantly different. At 28, 56, 84 d after fumigation treatment, there were no significant difference between the denitrification rates of four treatments. Compared with cotrol group, the diversity indexes and evenness indexes of nirS bacteria at 0, 14, 28, 56 and 84 d after fumigation treatments with 20, 100 and500 mg/kg were not significantly different. Except for 56 d, the bacterial community richness index at 0, 14, 28 and 84 d after 20 mg/kg fumigation were 8.77, 14.77, 9.77 and 8.75, respectively, which were significantly lower than those of the control group, the bacterial community richness index at 0, 14 and 28 d after 100 mg/kg fumigation were 10.76, 6.77 and 10.78, respectively, which were significantly lower than those of the control group, and there was no significant difference in the bacterial community richness index between the treated soil and the control group at 56 and 84 d after fumigation. The results showed that the denitrification was inhibited at 0-14 d after fumigation treatment with 500 mg/kg,and then the soil denitrification was restored at 28 d; the bacterial richness index with 500 mg/kg fumigation treatment had no significant difference in the early or the later periods from that of the control group. The metham-sodium effect on soil denitrification was independent with the changes of nirS bacterial community structure, and the nirS denitrifying bacteria did not play a major role in denitrification in soil.更多还原