Screening Of A Quinclorac-Degrading Strain And Its Mitigative Effect To The Phytotoxicity Of Tobacco

Quinclorac is a selective herbicide developed by BASF(Germany) for pre-emergence or postemergence control in rice. For the advantages of less dosage，long persistence and special efficiency on barnyard grass, quiclorac is widely used in agricultural production. However, degradation of quinclorac in acid soil is slow and cause serious damage on sensitive crops, especially in rice-tobacco rotation field, residual quinclorac in soil easily causes serious damage on tobacco growth and seriously affect the output and quantity of tobacco. Therefore, it is of great significance to study residue of quinclorac and its contamination to farmland environment.A bacterium strain designated as J3, able to degrade quinclorac efficiently, was isolated from soil with long-term application of quinclorac by enrichment culture method. Then, identification and degradation characteristic under different environmental factor of J3were conducted. Finally, bioremediation effect of J3on quinclorac injured tobacco was studied through pot experiment. The results were as follows:A bacterium strain designated as J3, able to degrade quinclorac efficiently, was isolated. Base on morphological characteristics,biochemical-physiological identification and sequence analysis of the16S rDNA, strain J3was identified as Alcaligenes sp..At initial quinclorac concentration of100mg/L and J3inoculation quantity of4%, more than70%of quinclorac was degraded in6days at pH7and temperature of30℃.At J3inoculation quantity of4%, temperature of25℃, quinclorac concentration of50%of its recommendation dose, the bioremediation rate of the potted tobacco(60d later after transplant) reached82.15%.