Denitrifying capacity of rhizobial strains of Argentine soils and herbicide sensitivity

Agrochemical application in soils is a matter of environmental concern, and among soil microorganisms, rhizobia and their action before different pesticides are interesting to study, due to their taxonomic and functional diversity. The objectives of the present work were to assess the capacity of rhizobial populations to use herbicides as source of nutrients, as well as their ability to reduce nitrates and / or denitrify. Eighty-one strains belonging to four populations of different genera of rhizobia (Rhizobium, Mesorhizobium, Ensifer and Bradyrhizobium) were assessed. The effect of glyphosate, 2,4-dichlorophenoxyacetic acid, and atrazine on growth of the strains, as well as the ability of the strains to act on herbicide transformation to reduce nitrate and denitrify, were evaluated. The genera studied showed different responses to pesticides. Bradyrhizobium had the greater capacity to utilize the herbicides and among the compounds evaluated, atrazine was the most used as a source of energy. To conclude, some Bradyrhizobium strains were able both to denitrify and to use the atrazine herbicide. The results obtained in this study increase expectations of the use of rhizobia as inoculants, causing changes at the agricultural and environmental level and allowing an appropriate management of agricultural soil fertilization, efficiency in nitrogen fixation and a faster biodegradation of pesticides in soil.

Fil: Vercellino, Magalí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina

Fil: Gomez, Marisa Anahi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina