Agronomic Efficiency of Grammy Crop® (Azospirillum brasilense) Under Different Application Methods in First- and Second-Crop Maize

The nutritional requirements of maize are some of the most studied factors in the production of this crop. It is known that nitrogen (N) is the major nutrient required by maize. Products based on microorganisms such as Azospirillum spp. can promote N fixation, providing yield gains. This study aimed to investigate the agronomic efficiency and feasibility of applying Grammy Crop® (Azospirillum brasilense-based product) by different methods to first- and second-crop maize. Experiments were conducted in two seasons between 2019 and 2020. In the first crop, a 4 × 7 factorial design was used, in which the first factor was locality (Candói, PR; Guarapuava, PR; Santa Maria do Oeste, PR; and Sertão, RS) and the second factor was treatment (untreated control, 75% N control, 100% N control, commercial A. brasilense-based inoculant, Grammy Crop® liquid seed treatment, Grammy Crop® peat-based seed treatment, and Grammy Crop® liquid foliar treatment). In the second crop, the factorial design was 3 × 7, with three localities (Pitanga, PR; São Miguel do Iguaçu, PR; and Serranópolis do Iguaçu, PR) and the same treatments. At physiological maturity, plants were evaluated for yield (kg ha-1), thousand grain weight (g), plant height (cm), shoot dry weight (kg ha-1), leaf N content (g kg-1), and grain N content (g kg-1). All treatments improved productive, vegetative, and nutritional parameters compared with the untreated control for all localities and crops. Grammy Crop® was efficient in improving maize yield under all methods of application, providing similar benefits as N fertilizer and a commercial inoculant.