Azospirillum brasilense INOCULATION ASSOCIATED WITH NITROGEN FERTILIZATION FOR THE DEVELOPMENT OF GRAIN SORGHUM

Abstract

Nitrogen fertilization in crop sorghum during the off-season may have a lower cost-benefit ratio than expected, due to the residual effect of the predecessor crop. However, the use of growth-promoting bacteria can be an economical alternative to increase crop yield in the Cerrado. The objective was to evaluate the response of grain sorghum to nitrogen fertilization and its inoculation by A. brasilense. A complete randomized block design in a 5 x 2 factorial arrangement was used, with five replications of the following treatments: recommended amount of N (120 kg ha-1 of N-urea), divided into 0 %-100 %, 25 % -75 %, 50 %-50 % and 100 %-0 %, in sowing and coverage, respectively, and the control (without N); with and without inoculation via sorghum seed. The morphological and productivity components of the crop were evaluated. The application of 100 % of N in the sowing provided larger plants and the 50 %-50 % installment provided smaller plants. The plants did not respond to inoculation by A. brasilense. The yield components of sorghum grown in succession to soybean, rainfed, do not change due to A. brasilense inoculation and supply or installment of nitrogen fertilization.