463 resultados para dióxido de nitrogênio


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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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This research examines the merits of hallucinogenic plants considered and/or psychoactive substances, such as Cannabis sativa and Ipomoea violacea, using the isotope rates of stable isotope of oxygen (18O) and nitrogen (15N), continuing projects already developed by the research group at the Center for Stable Isotope (CIE), which evaluated the isotopes carbon-13. This paper helps in creating a database that we intent to use in evaluation of each plant merit. Through the IRMS (Isotope-Ratio Mass Spectrometry) technique, it has shown that some of the 24 samples of marijuana (Cannabis sativa L.) evaluated were similar to those grown in the regions of Fairbanks and Tanacross Alaska, USA. In turn, the 50 samples of Ipomoea violacea, coming from Botucatu (SP) and Três Lagoas (MS), got their differences detected, in order to clearly identify the discrepancies between their growing regions. Thus, it was possible not only to track the geographical differences between marijuana samples collected from different regions, but also evaluate the isotopic variation of leaf, flower and seed of Ipomoea violacea. With this database, it was possible to determine the origin region of the drug and/or detect where the cultivation was carried out, aiding in the search of the traffic control agencies, such as the Federal Police in Brazil

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Pós-graduação em Agronomia - FEIS

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Technologies that increase crop yields are possible when providing profitability to the producer. The objective of this study was to evaluate production costs and profitability of maize in production systems in Cerrado. The study was conducted in Selviria (Mato Grosso do Sul State), Brazil, in the years 2009/10 and 2010/11. The experiment was arranged in randomized blocks with four replications in factorial and mixed with tracks. We established 36 treatments, three green manures (Pennisetum glaucum, Crotalaria juncea and intercropping Pennisetum glaucum + Crotalaria juncea), three soil management practices (no-tillage system, "heavy disking" + "levelling disking" and "chisel plow" + "levelling disking") and four doses of N (0, 60, 90 and 120 kg ha(-1)). For economic analysis were estimated operational cost, the gross revenue obtained by the product of the productivity of the treatments and the value of corn (R$ 0,417 kg or R$ 25,00 sc(-1)) and the ratio revenue / cost of treatment. Whereas higher values (revenue/cost > 1) and lower (revenue/cost ratio < 1) as a parameter in the analysis of profitability, it can be concluded that corn under no-tillage had the highest profitability in succession to Pennisetum glaucum growing profitability with increasing N rates, in succession to Crotalaria juncea and in the absence of nitrogen application on the coverage achieved higher profitability compared to other treatments and in succession to the consortium Pennisetum glaucum + Crotalaria juncea doses of N was between 50 and 55 kg ha(-1) offer greater profitability to the cultivation of corn.

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To achieve high wheat yield, correct management of N fertilization and the use of high yield potential cultivars are necessary. The aim of this study was to evaluate the effects of different application rates and sources of N, applied totally at sowing or in topdressing, on grain yield and yield components of two irrigated wheat cultivars under a no-till system, grown in a Cerrado (Brazilian tropical savanna) region of low altitude. A randomized block design was used in a 5 x 3 x 2 x 2 factorial arrangement with three replications, combining five levels of N (0, 50, 100, 150, and 200 kg ha(-1)), three sources of N (Entec (R), ammonium sulfate, and urea), and two application times (at sowing, near the rows, or in topdressing) in two wheat cultivars (IAC 370 and Embrapa 21). The wheat cultivars had similar grain yields. There was no difference among the sources of N for grain yield and yield components. The N applied totally at sowing did not differ from the traditional application at sowing and in topdressing for production of irrigated wheat in no-tillage. The increase in application rates of N increased the leaf N contents and chlorophyll, plant height, and the number of ears per m(2). Grain yield of the wheat cultivars IAC 370 and Embrapa 21 increased up to the application rates of 134 and 128 kg ha(-1) of N, respectively, regardless of application time and source of N. The positive correlation between chlorophyll leaf content and grain yield in accordance with N fertilization levels indicates that N fertilization in topdressing can be recommended based on SPAD readings of leaf chlorophyll performed at 38 days after wheat plant emergence.

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The objective of this study was to evaluate the rate of leaf appearance, leaf elongation rate, number of green leaves, length of blade and stem of Brachiaria brizantha cv. Marandu under different nitrogen levels and two residue heights. A randomized block design was used in a 4 x 2 factorial scheme, four doses of nitrogen (100, 200, 300 and 400 kg N ha(-1) year(-1)) and two residue heights (5 and 15 cm). There was significant interaction between residue height and nitrogen levels for leaf appearance rate of signal grass, which was influenced negatively and linearly by the residue heights being observed an average reduction of 28.20% from lower to higher residue. There was no interaction between the levels of nitrogen x residue height on the number of green leaves. The dosage that provided the highest stalk in the residue height of 5 cm was of 271.5 kg N ha(-1). An increase of 0.0745 cm tiller(-1) day(-1) for 1 kg of N ha(-1) applied to height of 15 cm of residue was observed. Nitrogen fertilization contributes positively to growth and development of rates of appearance and leaf extension. The management of pasture of Brachiaria brizantha cv. Marandu with 5 cm of residue and fertilization with 100 kg N ha(-1) provided better answer morphogenic traits.