The objective of this work is to study the agronomic performance and genetic divergence in corn in the Cerrado-Amazon ecotone. The trials were conducted in the 2017/18 harvest at a property in the state of Pará. The experimental design was a randomized block with nine treatments and three replications, where the treatments are represented by nine cultivars of corn. The characteristics to evaluate agronomic performance and genetic divergence were: ear height (cm), plant height (cm), ear length (cm), ear diameter (mm), number of rows, number of grains per row and grain yield (kg ha−1). The cultivars were separated into a multivariate model in five groups using the Tocher optimization method. The cultivar AG 1051 showed the best agronomic performance. The results of genetic divergence were according to the generalized distance of Mahalanobis (D2), with the commences AG 8088 x CATIVERDE and AG 1051 x AL BANDEIRANTE, the most promising for future crosses.

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Due to its high economical importance and the need of high amounts of nitrogen fertilizer, the corn crop demands further and deeper studies on biological nitrogen fixation trough bacterium Azospirillum brasilense. Therefore, this study aimed at assessing influence of inoculation of three different genotypes (Orion, A1 Bandeirante and AG-1051) with such bacterium in association with cover application of five different nitrogen doses on percentage oil content in the grains. Data were subjected to ANOVA and means compared by Tukey test at 5%. The inoculation of A. brasilense, with or without nitrogen fertilization, has promoted oil content increase in the grains. Orion genotype presented the greatest increase with the bacterium inoculation, as well as it was the most productive at the lowest nitrogen dosages assessed. High temperatures favored the increase in the oil content in the grains. Keywords: Zea mays, inoculation, biological fixation, oil EFEITOS DA INOCULAÇÃO COM Azospirillum brasilense E DOSE DE NITROGÊNIO SOBRE O TEOR DE ÓLEO DE MILHO RESUMODevido à sua grande importância econômica e necessidade de fertilizantes nitrogenados, a cultura do milho exige estudos mais aprofundados sobre a fixação biológica do nitrogênio pela bactéria Azospirillum brasilense. Portanto, este estudo teve como objetivo avaliar a influência da inoculação de três diferentes genótipos (Orion, A1 Bandeirante e AG-1051) com essa bactéria em associação com a aplicação de cinco diferentes doses de nitrogênio no teor percentual de óleo nos grãos. Os dados foram submetidos à ANOVA e as médias comparadas pelo teste de Tukey a 5%. A inoculação de A. brasilense, com ou sem adubação nitrogenada, promoveu aumento do teor de óleo nos grãos. O genótipo Orion apresentou o maior aumento com a inoculação da bactéria, bem como o mais produtivo nas menores dosagens de nitrogênio avaliadas. As temperaturas altas favorecem ou aumentam o teor de óleo nos grãos.           Palavras-chave: Zea mays, inoculação, fixação biológica, óleo

Brazil, a major meat producer and exporter, has the largest commercial herd in the world with about 215 million heads, as Pará is in the 4th position in number of cattle in the country, with 22 million heads. In the country 80% of the farms are beef cattle, having reared in all Brazilian municipalities, mostly calf production, many producers do not have the records of information on the cost of production and the viability of the business, sensitivity analysis and important instrument, and of total importance because it helps to know the results, profitability for decision making. Thus, this objective was to make a sensitivity analysis, for this we made a case study, where zootechnical indexes were raised, the support of the property and made a projection of the herd, during the period of 10 years, to find the revenue and verified the expenses both fixed as the variable, and also investments in the infrastructure to find the expenses of the property in the period, the economic indexes were found and sensitivity analysis was made, in a rural property in Santa Maria das Barreiras, in the State of Pará. Concluding that project is robust and feasible, with attention to expected profitability.The creation of beef cattle and an activity that is present in almost all Brazilian municipalities, being commonly used in cattle farming the production of calves, or fattening, or even producers that can produce the complete cycle of production, creates, recreates and fattening, always seeking the highest profitability, with Diogo Claudio da Silva et al.

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