Desempenho e análise econômica da produção de biomassa e grão de milho com Azospirillum brasiliense associado a fertilizantes nitrogenados de eficiência aumentada.

Abstract

The objective of this work was to evaluate the effect of Azospirillum brasiliense associated with nitrogen fertilizers of increased efficiency in corn grown in the Carajás region. The experimental design adopted was completely randomized, in a 5 x 3 x 2 factorial scheme,with six replications. The factors studied were: i) factor A - Five doses of N applied incoverage (0; 50; 100; 150 and 200 kg ha-1of N) at the phenological stage V4; ii) factor B -three sources of N (urea, urea with urease inhibitor and coated urea); and iii) factor C - withand without seed inoculation with Azospirillum brasiliense. The inoculant dose was 100 mL ha-1 containing strains of the bacterium at a minimum concentration of 2 x 108 viable mL-1cells. The following plant phytotechnical evaluations were carried out: average plant height,average ear insertion height, average stem diameter, prolificacy, average ear length, average ear diameter, average number of rows per ear, average number of grains per row and cob mass without straw. Assessments of nutritional status through the variables: non-destructive determination of chlorophyll “a”, “b” and total on the leaf; efficiency in the use of fertilizer. There was an interaction (P <0.05) between the inoculation factors and nitrogen doses forstem diameter, leaf area index, A, B and total chlorophyll, root length, root width, root drymatter production. While, the variables, height, leaf dry mass and stem dry mass did notpresent significant interaction, however the factors, dose, source and azospirillum influencedin isolation. The dose of 100 kg ha-1of N in the urease inhibitory source promotes greater height of the corn plants. The inoculation of corn seeds with Azospirillum brasiliense increases the leaf area and the production of dry mass of the aerial and root parts