Improvement of maize yield by foliar application of Azospirillum brasilense Az39

Abstract

Azospirillum brasilense is a plant growth promoting bacteria (PGPB) widely used as an inoculant in diverse species, including maize (Zea mays L.) to improve their growth, development and productivity. Its ability to survive to the presence of herbicides has been demonstrated. Currently, the effectiveness of foliar application of biological formulations takes advantage of the intrinsic capacity of bacteria, regardless of the edaphic conditions of the soil. The objective of this work was to evaluate the effects of the foliar inoculation of A. brasilense Az39 in maize crop with different combinations of herbicides to increase production and to improve sustainable management practices. The field study was performed during three successive seasons. In the growing seasons between 2015 and 2018, different combinations of glyphosate and atrazine were evaluated with and without the foliar inoculation of Az39. A higher yield and total chlorophyll content were observed, together with a lower damage of membranes in the treatment with foliar inoculation of Az39, one application of atrazine and two applications of glyphosate. The yield varied between seasons but in all of them, the foliar inoculations with Az39 benefited the crop. Therefore, application of A. brasilense Az39 improves the performance of the maize crop under suitable combinations of herbicides based upon cost and environmental risk. These results, obtained with PGPB native strains, demonstrate its complementary benefits for the development of sustainable crop production practices.