Associação de Azospirillum brasilense com ureia convencional e fertilizante nitrogenado de eficiência aumentada no crescimento, trocas gasosas e teor nutricional em híbrido de milho.

Abstract

One of the limiting factors in the productivity of corn in the State of Pará is the lack of information regarding the benefits of adopting growth-promoting bacteria and the management of nitrogen fertilization. In general, farmers have adapted the recommendations for fertilizing maize grown in the south of the country for the northern states, since research data for the crop is scarce in the region. In turn, due to differences in yield potential between corn hybrids, fertilizer doses may be overestimated and / or underestimated. Thus, this study aimed to evaluate the vegetative, physiological and nutritional status of corn inoculated with Azospirillum brasilense associated with nitrogen sources and doses. The experiment was carried out in a complete randomized block design, in a 4 x 2 x 2 factorial scheme, with four replicates each, as specified: four doses of N (0; 60; 120 and 180 kg ha-1 of N), two sources of N (common urea and urea treated with urease inhibitor - NBPT) and absence and presence of inoculation with Azospirillum brasilense. The evaluations consisted of the vegetative growth of the plant, the gas exchange and the concentration of macronutrients in the root, stem and leaf of the corn. The results identified that the inoculation of the corn seeds with the bacteria and the use of nitrogen fertilization, regardless of the sources, promoted an improvement in the vegetative growth of the hybrid, improving the vegetative development and the physiological responses of corn, especially when applied at 120 kg ha-1 of N. The increase in N doses and inoculation with the bacterium also influenced the concentration of macronutrients in corn. However, the dose of 180 kg ha-1 of N associated with seed inoculation with Azospirillum brasilense, provided a higher concentration of macronutrients in corn, regardless of the application of common urea or urea treated with a urease inhibitor.