摘要
吡虫啉(Imidacloprid)是近年来国内外普遍使用的新型高效烟碱类广谱杀虫剂,残留期约25 d,对土壤有益微生物的生物风险有待评估。利用固、液培养技术,以3株溶解无机磷的伯克霍尔德氏菌(Burkholderia Yabunchi B05,B07和B09)为对象,设置0、5、10、20 mg·L–1浓度的吡虫啉处理,研究无机磷细菌(Inorganic phosphate-solubilizing bacteria,IPSB)的生长繁殖、对Ca3(PO4)2的溶解及其机理。结果表明,在固体培养时,吡虫啉显著抑制IPSB生长,但菌株不同抑制程度各异,菌落直径的降幅高达39.81%~55.45%;供试IPSB菌株不同,吡虫啉对它们溶解Ca3(PO4)2能力的影响也不一样,降低B09但提高B05和B07的溶磷圈直径和溶磷指数。在液体培养时,吡虫啉也抑制IPSB生长,菌密度降低49.87%~65.28%。吡虫啉对IPSB溶磷量的影响因浓度和菌株不同而异。具体表现为全浓度范围促进B05溶解无机磷;中、低浓度吡虫啉对B07溶解Ca3(PO4)2无显著影响,高浓度有促进作用;低浓度吡虫啉对B09溶解Ca3(PO4)2无显著影响,中、高浓度产生抑制作用。供试3株IPSB均能分泌氢离子(H+)、草酸和柠檬酸。除此之外,B05和B07可分泌乙酸,B07还会分泌琥珀酸,B09可分泌苹果酸。在分泌的这些有机酸中,草酸和柠檬酸分泌量最多,合计占有机酸分泌总量的67.65%~83.28%。吡虫啉不同程度地抑制IPSB分泌H+,但对IPSB分泌有机酸的影响因浓度、菌株和有机酸种类不同而表现出多样性。供试IPSB有机酸分泌总量和H+分泌量分别与Ca3(PO4)2溶解量呈显著线性正相关(r有机酸=0.876和H+r=0.823,P<0.05,n=12)。总之,吡虫啉显著抑制IPSB生长繁殖,通过改变有机酸和H+的分泌而影响Ca3(PO4)2溶解。农业生产中,施用吡虫啉影响土壤IPSB的代谢、种群结构和溶磷作用。
【Objective】Imidacloprid,a new type of neonicotinoid insecticide with high pest control efficiency,is widely used in recent years.As this chemical insecticide has a long residual period(about 25 days),it is necessary to evaluate risks it might pose to beneficial microbes in the soils.【Method】Solid and liquid incubations were carried out simultaneously to investigate effects of the insecticide on growth,reproduction,and phosphorus(P)dissolving capacity of inorganic phosphate-solubilizing bacteria(IPSB),such as Burkholderia Yabunchi B05,B07 and B09,relative to concentrations of imidacloprid(0,5,10,and 20 mg·L–1).【Results】Imidacloprid inhibited to a varying extent the growth and reproduction of all the three strains of IPSB,with the diameter of bacterial colonies decreased by 39.81%~55.45%in solid incubation.The tested bacteria varied in solubilization of tricalcium phosphate in response to imidacloprid.B09 was lowered in diameter of P-dissolving halos and index in the presence of imidacloprid,but B05 and B07 behaved otherwise,with the diameter of P-dissolving halos and index reaching as high as 9.72%~19.44%and 40.69%~106.94%,respectively.In liquid incubations,imidacloprid also inhibited growth and reproduction of the three strains of IPSB,with the bacterial density decreased by 49.87%~65.28%in culture solutions.P solubilization capacibility of the bacterial strains varied with imidacloprid concentrations.Imidacloprid,regardless of concentration,stimulated P solubilization of B05.P solubilization of B07 varied in solutions low or mediumin concentration of imidacloprid,but increased in those high in imidacloprid concentrations compared with CK(without imidacloprid).B09 showed a similar tread to B07 in variation of P dissolving capacity in solutions low in imidacloprid concentrations,while it decreased greatly in solution medium or high in imidacloprid concentrations.All the three strains of bacteria were able to excrete protons,oxalate,and citrate.Oxalate and citrate accounted for 67.65%~83.28%of the total organic acids excreted.In addition,acetate was detected in culture solution with B05 and B07,malate with B09,and succinate with B07.Excretion of the organic acids was affected by not only imidacloprid concentration,but also strain of bacteria and type of organic acid.Furthermore,imidacloprid inhibited bacterial proton secretion by a varying degrees.The amount of P dissolved from tricalcium phosphate was positively related to the excretion of total organic acids(r=0.876,P<0.05,n=12)and to that of protons(r=0.823,P<0.05,n=12)as well.【Conclusion】It could be concluded that imidacloprid inhibites growth and reproduction of the IPSB by a varying degree in the soil,thus affecting the effects of the bacterial excreting organic acids and protons,and hence the effect of promoting or inhibiting and P solubilization.So in pest controlling application of a large amount of imidacloprid could influence the activities,numbers,and functions of IPSB to a various extent,depending on type of the soil and group of IPSB.
作者
郑丽霞
王玉书
刘海
黄建国
ZHENG Lixia;WANG Yushu;LIU Hai;HUANG Jianguo(College of Resources and Environment,Southwest University,Chongqing 400716,China;Institute of Agricultural Science and Technology Information,Guizhou Academy of Agricultural Sciences,Guiyang 550006,China)
出处
《土壤学报》
CAS
CSCD
北大核心
2020年第1期174-182,共9页
Acta Pedologica Sinica
基金
重庆市科委重点项目(CSTC2018jscx-mszd0133)
贵州省烟草公司遵义市公司科研项目(201503)资助~~
关键词
吡虫啉
无机磷细菌
溶磷
Imidacloprid
Inorganic phosphate-solubilizing bacteria
Phosphorus solubilization