Effects of atrazine-mineralizing microorganisms on weed growth in atrazine-treated soils.

摘要

The herbicidal effect of atrazine on sensitive plant species was studied in soils inoculated with bacteria capable of mineralizing atrazine. Nasturtium officinale and Solanum nigrum plants died within 15 days after sowing in soil containing atrazineincorporated at 4 mg kg-1. N. officinale grew normally when 5 mg kg-1 atrazine-mineralizing bacteria was mixed into the soil containing atrazine, prior to seeding. Atrazine concentrations in the soil declined by 90% within 5 days as a result of degradation by bacteria added to the soil. Normal growth of S. nigrum plants was observed in soils receiving only 0.1 mg kg-1 atrazine-degrading bacteria. The efficacy of atrazine in the presence of atrazine-degrading bacteria was also tested on N. officinale and Agrostis tenuis [A. capillaris] in greenhouse trials under simulated field conditions, using a commercial atrazine formulation, by spraying the herbicide onto soil in open containers. Microbial herbicide breakdown was rapid and the effect of the herbicide on the indicator plants was drastically reduced when the soil was kept under conditions favourable for the atrazine-degrading bacteria.