Seed and leaf-spray inoculation of PGPR in brachiarias (Urochloa spp.) as an economic and environmental opportunity to improve plant growth, forage yield and nutrient status

Brazil has 180 Mha of pastures, 86 occupied with Urochloa spp. (syn. Brachiaria), and 70% in some level degradation. Inoculation plant-growth-promoting bacteria (PGPR) may represent an economic environmental feasible strategy to improve pasture production. Two greenhouse seven field trials were performed verify the effects seed inoculation at sowing or leaf-spray established pastures elite strains Azospirillum brasilense Pseudomonas fluorescens. All plants received nutrients including 40 kg ha?1 N sowing, half treatments a supply 30 days after emergence. A. increased shoot biomass by average 16.8% both inoculation, whereas P. fluorescens 15.2 14.2%, respectively, always higher extra N. Seed content 11.7 20.7%, K 9.9 11.3%, respectively; for increases 33.3 36.6% P, 10.6 13.6% K, respectively. Benefits mainly attributed improvements root architecture synthesis phytohormones. Biological nitrogen fixation brasilense, P acquisition (solubilization phosphates siderophores synthesis) ACC-deaminase also contributed plant growth nutrient status. PGPR translated into more fodder improved nutritional value feed livestock, representing promising environmentally-friendly tropical pastures.