草甘膦对土壤微生物的影响

以东北地区黑土为材料,探讨草甘膦对土壤呼吸、土壤可培养菌种群数量、大豆固氮根瘤菌和大豆根腐镰刀菌数量的影响。研究结果表明,随着草甘膦浓度的加大,土壤呼吸的抑制作用增强,土壤中草甘膦含量为1mg.kg^-1、10mg.kg^-1、100mg.kg^-1时,危害系数分别为1.20、0.322、0.076,远小于无危害标准系数20,确定草甘膦对土壤微生物低毒或无实际危害。不同浓度的草甘膦对土壤真菌、放线菌种群数量具有一定影响。土壤可培养菌种群数量随草甘膦浓度的升高抑制作用逐渐增强,随着草甘膦加入时间的延长,真菌、细菌、放线菌的种群数量有所恢复,其中放线菌与真菌同细菌相比对草甘膦敏感,土壤细菌对草甘膦具有较强的耐受或降解能力。草甘膦对大豆根瘤菌和大豆根腐镰刀菌有一定影响,对大豆根瘤菌的抑制作用与草甘膦浓度呈正比;低浓度草甘膦对镰刀菌产生激活作用,高浓度草甘膦对镰刀菌具有抑制作用;伴随草甘膦加入时间的延长,其对大豆根瘤菌和大豆根腐镰刀菌的抑制作用逐渐减弱。

Effects of glyphosate on soil microorganisms

Black soil in northeast region of China was used to investigate the effects of glyphosate on soil respiration,soil cultural bacteria,Rhizobium japonicum and Fusarium oxysporum,to provide a theoretical basis for the evaluation of environmental safety of glyphosate.The results showed that increasing glyphosate concentration increased the inhibition on soil respiration.When glyphosate concentration in soil were 1mg·kg-1,10mg·kg-1 and 100 mg·kg-1,the risk index were 1.20,0.322 and 0.076,which were less than the standard index of 20.Glyphosate influenced quantities of soil fungi and actinomycetes.High glyphosate concentration increased the inhibition to population of soil cultural bacteria.With the extended application of glyphosate,soil fungus,bacteria and actinomycetes populations had been restored.Actinomycetes were more sensitive to glyphosate than fungus and bacteria,and soil bacteria had a strong tolerance or degrading ability to glyphosate.Glyphosate impacted on inhibiting Rhizobium japonicum and Fusarium oxysporum,and the inhibition of Rhizobium japonicum was in direct proportion with the concentration of glyphosate.Low glyphosate concentration promoted Fusarium oxysporum populations,while high concentration inhibited them.The extended application time of glyphosate decreased the inhibition of glyphosate on Rhizobium japonicum and Fusarium oxysporum.