EFICIÊNCIA DA BACTÉRIA METHYLOBACTERIUM SYMBIOTICUM E AZOSPIRILLUM BRASILENSE NA FIXAÇÃO BIOLÓGICA DE NITROGÊNIO E PROMOÇÃO DE CRESCIMENTO NA CULTURA DO MILHO

Nitrogen fertilization is primarily responsible for increased productivity in corn crops; however, its application increases production costs and causes a series of environmental problems. An alternative to reduce the use of nitrogen fertilizers is the use of nitrogen-fixing bacteria.Therefore, this study aimed to evaluate the agronomic efficiency of the bacteria Methylobacterium symbioticum and Azospirillum brasilense in biological nitrogen fixation and growth promotion in corn crops. The experiment was conducted at the Várzea Grande University Center (UNIVAG), using a randomized block design with seven treatments: Nitrogen fertilization (total dose - control); 50% nitrogen fertilization + Methylobacterium symbioticum; 50% nitrogen fertilization + Azospirillum brasilense; Methylobacterium symbioticum isolated; Azospirillum brasilense isolated; Methylobacterium symbioticum + Azospirillum brasilense + 50% of nitrogen fertilization; and Methylobacterium symbioticum + Azospirillum brasilense, with three replicates. At flowering, the following were evaluated: plant height (cm), height of insertion of the first ear (cm), stem diameter (mm), green and dry mass of the aerial part (g/plant) and leaf nitrogen content (g/kg MS); at physiological maturity, productivity (kg/ha). The use of nitrogen-fixing bacteria did not provide significant differences in the morphological and productive parameters of the corn crop. Therefore, the use of bacteria is a viable alternative for the producer to reduce the amount of nitrogen fertilizers applied to the soil, since they did not provide a reduction in the evaluated parameters when in the absence and reduction of nitrogen fertilization.