138 resultados para Defoliation
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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV
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This experiment was conducted to evaluate the effect of grazing heights on daytime behavioral activities of Nellore beef cattle in the rainy season. The experimental area was 12 hectares divided into paddocks of one hectare each. The treatments consisted of four defoliation heights (15, 30, 45 and 60 cm) in pastures of Brachiaria brizantha cv. Xaraes with three replicates each. It was used the continuos grazing method, with variable stocking rate. Forage samples collected on the plots were sent to the laboratory for separation of the botanical components, weighing and determination of dry matter, with the material collected by simulated grazing. The variables: grazing time, idle time and ruminating time were evaluated for 12 consecutive hours on days 15 and 16 February 2011, considering the morning and afternoon periods. It was used a completely randomized design. The height of the canopy significantly influenced the daily grazing time and ruminating time, with a quadratic response as a function of time of defoliation. The bite rate decreased as a function of heights studied. However the chemical composition of the material collected by simulated grazing did not differ between treatments. Xaraes grass swards grazed at around 45 cm height provide greater ease of apprehension by grazing cattle.
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The objective of this study was to analyze the production of dry mass, forage accumulation rate and the structural composition of Brachiaria brizantha cv. Xaraes pastures, managed under different grazing heights in continuous stocking. The experimental area was 12 hectares, divided in paddocks of one hectare each. The treatments were 15, 30, 45 and 60 cm of defoliation heights. Nellore steers were used to reach the desired heights. Every 28 days four cut samples and eight visual samples were collected for comparative performance in the experimental plots. Two grazing exclusion cages were used per treatment to estimate accumulation rates kg.ha(-1) DM. The cut material was taken to the laboratory for separation of the botanical components (green leaf, stem and senescent material), weighing and determination of dry matter. The experimental design was the completely randomized with three replicates. There were treatments effects at all seasons for the production of total mass, except in the spring. In summer and spring seasons it was observed the highest values for leaf blades (1.100 kg DM.ha(-1)). In the winter, the highest values of senescent material was observed, as expected. The average accumulation showed no significant difference among the treatments, except for stem and total mass in the summer and stem in the fall. The tillers were heavier and higher values for number of green leaves per tiller occurred in the fall, but for senescent leaves per tiller ocurred in the winter. Swards grazed at heights between 45 and 60 cm of defoliation, had good production of forage mass and leaf constituent.
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The objective of this study was to determine the best height of the Tanzania grass under grazing, assessing morphological and productive characteristics of the sward. This experiment was conducted in Cidade Gaucha, Parana, where he was rated the accumulation rate and morphological characteristics of Tanzania grass pastures grazed at 20, 40, 60 and 80 cm grazing under continuous stocking with variable stocking rate for beef cattle. The experimental area was 12 hectare divided in paddocks of one hectare each. For each paddock were allocated two grazing exclusion cage for estimating herbage accumulation, and eight samples were taken every 28 days throughout the year 2010. The completely randomized design. The herbage mass of the morphological structures showed a linear positive function of sward heights. The height of defoliation did not influence the rate of herbage accumulation for any of the morphological structures: green leaf, stem + sheaths and senescent material. There were also no differences in leaf: stem ratio. All heights within the range studied provided adequate number of green leaves per tiller. Tanzania grass pastures grazed under continuous stocking between 40 and 60 cm, for providing a good association between accumulation and mass of green leaf blades, and acceptable values of the mass of stem + sheaths and senescent material. Pasture of Tanzania grass under 60 and 80 cm allow of leaves satisfactory accumulation in the autumn.
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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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.
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Pós-graduação em Ciência Florestal - FCA
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The aim of this study was to evaluate the influence of fine and medium droplets in the performance of flutriafol and thiophanate methyl + flutriafol for the control of Asian Soybean Rust (Phakopsora pachyrhizi Sydow & Sydow). The experiment was a 2 x 2 factorial design (2 droplet sizes x 2 fungicides) resulting in four treatments with six replications. The experimental area was set up with 24 plots (50 x 21 m). In each plot there was a central assessment area with 10 x 20 m. To the each plot there was a non-treated area placed in opposed direction to the wind. The evaluations of rust control were made by of the calculation of incidence (percentage of plants with rust), severity (level of infection), defoliations and soybean yield. The results were analyzed by the calculation of the confidence interval at 90%. The study was set up in curative control conditions with average infestation of 68.6%, average severity in the lower part of the canopy was of 35.9% and on the upper parte it was 4.57%. The results of severity, defoliation and productivity did not show statistical difference among the treatments. However, it was observed that in general there was tendency of better results with the application of flutriafol alone comparing with thiophanate methyl + flutriafol, since there was a small difference between two commercial products in the flutriafol active ingredient content (62.5 g ha-1 to the flutriafol alone and 60 g ha-1 to the thiophanate methyl + flutriafol). There was no statistical difference between fine and medium droplets. This fact can be explained by the characteristics of systemic action of the flutriafol and by the type of control made (curative). The flutriafol, being a systemic fungicide is less sensitive to the better coverage provided by the smaller droplets and, on the curative control, the amount of product deposited can became more import than coverage, mainly on the superior part of the leaves. These leaves are healthier than the inferior leaves that in general are the first to become completely compromised by the rust, losing importance to the plant. By this reason, medium droplets appear to have offered similar performance even not offering advantages in the leaf coverage. This fact may become important because in the practical side of the use of medium droplets, since this may increase the amount of time to spray, mainly because the fine and very fine droplets have more limitations related to drift and evaporation.
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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV
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Pós-graduação em Agronomia (Horticultura) - FCA
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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV