938 resultados para Doses de potássio
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia - FEIS
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Understanding the influence of vinasse application on trash decomposition and its effects on soil chemical attributes and sugar cane culture is essential for the good management of the production system. The objective of this study was to assess the time of decomposition and nutrient cycling of the green ratoon cane's trash, and their effects on soil fertility and technological components of crops, in terms of vinasse doses. The study was developed in the northwest region of Sao Paulo State - Brazil, under Eutrophic Ultisol, using the RB855453 variety. The experimental design was randomized blocks with split plot in time. The treatments were composed of four doses of vinasse (0, 50, 100 and 200 m(3) ha(-1)). There was a 20.9% reduction in the amount of crop residue remaining after one year review. The vinasse doses increased the ratoon cane's yield, without interfering in the raw material quality. The green cane system, in which the trash is deposited on the soil and vinasse application, changes the dynamics of the trash decomposition and modifies the soil fertility, contributing positively to the crop yield.
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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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This study was aimed to test low doses of a GnRH agonist, deslorelin acetate (DA), for induction of multiple ovulations in mares and to determine its impact upon their reproductive efficiency. Seven mares aging from 8-20 years were used in three consecutive reproductive cycles. Mares were initially monitored by ultrasound irrespectively of cycle stage, inseminated and submitted to embryo collection (EC) (T1). Immediately after, mares received 7.5 mg dinoprost tromothamine (DT) and were monitored by ultrasound twice a day until larger follicle reached 23-25mm and the second >18mm (T2). At this time point, mares received 100 mu g DA and ovulation was induced with 1000 mu g DA and 1000IU hCG when largest follicle reached 33-35mm in diameter, followed by EC. Mares were further allocated to T3 when received 7.5 mg DT after EC on 12 and 100 mu g DA 48 h later. DA treatment was performed until dominant follicle reached 34 +/- 1 mm or 6 days of application. All EC were performed 8 days after ovulation. Mares with multiple ovulations in T1, T2 and T3 were 14.28% (1/7), 100.00% (7/7) and 0.00% (0/7), respectively, and averaged 0.43 +/- 0.53 in T1, 0.86 +/- 0.38 in T2 and 0.00 in T3 embryos per donor, respectively. Embryo recovery rate was 43.00% in T1, 85.71% in T2 and 0.00% T3. In conclusion, use of DA in mares with follicles larger than 25mm enhanced dominant and co-dominant follicle growth, that ultimately increased the incidence of multiple ovulations and embryo recovery rate.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The proper mineral fertilization of guava orchards under intensive management, is a major factor in productivity and monitoring the nutritional status of the plants contributes to the efficiency of this agronomic practice. The aim of this study was to investigate different doses of nitrogen and potassium in the nutritional status of guava 'Paluma'. The experiment was conducted at Vista Alegre do Alto, Sao Paulo, in a 7 year old irrigated orchard, managed with fruiting pruning during four consecutive growing seasons. The soil is a dystrophic Ultisol. The experimental design was randomized blocks, in factorial, with four nitrogen doses (0, 0.5, 1 and 2 kg of N plant(-1)) and four of potassium (0, 0.55, 1.1 and 2.2 kg of K2O plant(-1)), with three replications. Nitrogen fertilization promoted increased levels of leaf N and Mn and the decrease in the levels of P and B; effects observed from the second to the fourth production cycle. Nitrogen fertilization increased the Ca and Mg levels, respectively, in the second and third cycle. Except for the first production cycle, K and Mn foliar concentrations increased with increasing potassium fertilization, whereas the levels of Mg, in the second and the fourth cycle, decreased as a function of fertilization.
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The nutrition of the orchards is the major factor of productivity, being necessary to know the proper doses of fertilizers and their influence on fruit quality attributes for industrialization. This study evaluated the effects of different doses of nitrogen and potassium on the productivity of guava trees and also on the values of pH, soluble solids (SS), titratable acidity (TA) and pulp/kernel ratio of guavas. The experiment was conducted at Vista Alegre do Alto, SP in an irrigated 'Paluma'guava orchard, 7 years old, managed with pruning during three consecutive cycles of production. The soil of the area was dystrophic Ultisol. The experimental design was the randomized blocks, in factorial, with four nitrogen doses (0, 0.5, 1 and 2 kg of N plant(-1)) and four of potassium (0, 0.55, 1.1 and 2.2 kg of K2O plant(-1)), with three replications. Nitrogen fertilization increased productivity and the pH of the fruit, being explained by the quadratic polynomial regression models; reduced linearly the pulp/kernel ratio and do not influenced the SS and TA values. On the other hand, potassium fertilization and N x K interaction had no significant effects on productivity and the other characteristics evaluated.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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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.