Wheat Grain Response to Nitrogen Fertilization and Field Inoculation with a Liquid Formulation of Azospirillum brasilense.
Martin Diaz-Zorita, CONICET-FAUBA and Nitragin Argentina SA, Calle 10 y 11, Parque Industrial Pilar, Pilar - Buenos Aires, 1629, Argentina and John Grove, Univ of Kentucky, Dept of Agronomy, N122 Ag Science North, Lexington, KY 40546-0091.
Beneficial effects of inoculating with Azospirillum brasilense on crop productivity have been widely described. However, the relationship between the grain yield response of the inoculated crop and fertilization is not well documented. Our objective was to evaluate the effects of on-seed inoculation with a liquid formulation of Azospirillum brasilense strain Az39 on dryland grain productivity of wheat under different N fertilization treatments in two contrasting temperate environments. The study was performed in during the 2005 growing seasons in Kentucky and the Pampas (Argentina) on Alfisols and Mollisols, respectively. At both sites, wheat grain yield increased with increasing N fertilization rate, independently of the inoculation treatment. The grain yields were greater with inoculation, giving a mean grain response of 250 kg ha-1 (8 %). Leaf and grain N concentrations were greater at higher N fertilization rates but were not significantly effected by inoculation. Both practices (N fertilization and on-seed inoculation) improved yield by raising the grain number per unit area, a response to better early crop growth rates. The use of this liquid formulation providing Azospirillum brasilense, in combination with an adequate N fertilization, contributed to increased dryland wheat yields in temperate region production systems.