977 resultados para atributos químicos


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The objective of this work was to typify, through physicochemical parameters, honey from Campos do Jordão’s microrregion, and verify how samples are grouped in accordance with the climatic production seasonality (summer and winter). It were assessed 30 samples of honey from beekeepers located in the cities of Monteiro Lobato, Campos do Jordão, Santo Antonio do Pinhal e São Bento do Sapucaí-SP, regarding both periods of honey production (November to February; July to September, during 2007 and 2008; n = 30). Samples were submitted to physicochemical analysis of total acidity, pH, humidity, water activity, density, aminoacids, ashes, color and electrical conductivity, identifying physicochemical standards of honey samples from both periods of production. Next, we carried out a cluster analysis of data using k-means algorithm, which grouped the samples into two classes (summer and winter). Thus, there was a supervised training of an Artificial Neural Network (ANN) using backpropagation algorithm. According to the analysis, the knowledge gained through the ANN classified the samples with 80% accuracy. It was observed that the ANNs have proved an effective tool to group samples of honey of the region of Campos do Jordao according to their physicochemical characteristics, depending on the different production periods.

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In Brazil, the exploration and use of the Hevea brasiliensis Mull Arg. wood at the end of the latex production cycle from 30 to 35 years, is practically unknown. However, one of the most significant problems with its use relates to the high susceptibility of this species wood to the fungus Botryodiplodia theobromae attack, especially during the primary wood processing phase. The present study evaluated the efficacy of four chemicals to control juvenile and adult Hevea brasiliensis wood from the attack of the fungus stainer Botryodiplodia theobromae following the ASTM 4445 (2003) standard. The results showed that the active ingredients separately tested and evaluated in the laboratory; (Quinolinolato Copper - 8 and Carbendazim (T1); Tribromofenol 2-4-6 (T2); Extract-Based Vegetable Tannin (T3); Carbendazim and Prochloraz (T4)) do not totally prevent the contamination of Botryodiplodia theobromae in 5% level of significance

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The evolution of sugar cane mechanized harvesting made the sector to question the current row spacing used due to its influence on soil compaction. The aim of this study was to evaluate the soil hydro-physical attributes in two row spacings after the farm machinery traffic. The treatments were conducted in a randomized block design with twelve repetitions, being subjected to the variance analyze in double factorial arrangement. The bulk density, the gravimetric water content, and the soil cone index along the position of crop lines (LC) and 0,1m from the row (LP) at the range of depth of 0 to 0.2m and 0.2 to 0.4m were assessed in both row spacings after the fourth harvest season. The results showed that the row spacings of 1.4 and 1.5m did not affect the values of bulk density and gravimetric water content of the soil in all ranges of depth and sample positions studied. However, in the depth range of 0.2 to 0.4 m, the values of soil cone index (IC) in the row spacing of 1.5 m were higher than the values in row spacing of 1.4 m, at both sampling positions. Regardless of row spacing and sample position, the values of soil cone index in the depth range of 0.2 to 0.4m were higher than the depth range of 0 to 0.2m.

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The electrical measures of the soil have been used as variables that correlate with its characteristics. This study aimed at developing an electrical capacitance sensor of low cost, to evaluate its performance on the field and verify the correlation between the measurements of electrical capacitance with physical properties (sand, silt and clay) and chemical properties of soil (pH, MO, P resin, H + Al, K, Ca, Mg, SB, CTC and V%) and the moisture content. The data sampling was performed at the farm named "Capão da Onça" which belongs to the State University of Ponta Grossa. The samples collection was conducted in an area of approximately 13 hectares, totalizing 81 samples. In each sampling the electrical capacitance of the soil was measured. After the sensor withdrawal, soil samples were collected and sent to be analysed in the laboratory of the College of Agronomics Science of the Paulista State University. The measuring instrument used to collect data on electric capacitance of the soil a digital multimeter was used. The data were submitted to the analysis of correlation and regression. The developed system presented a low cost and it was capable to measuring variation of the electrical capacitance of the soil. The obtained measures satisfactorily correlated with the levels of clay and sand, and weakly with the moisture content. This had demonstrated the possibility to use a sensor to verify the soil texture in not homogeneous areas. The measures of the electrical capacitance of the soil obtained by the sensor had significantly correlated with the soil attributes: calcium, magnesium, pH, SB and CTC. These results had demonstrated the possibility to use a sensor for soil fertility control.

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Marchantia polymorpha develops under environmental conditions of high relative humidity and shading. As this habitat is the usually used in nurseries for the growth of seedlings of native tree species that species grows very quickly among developing tree seedlings and causes severe losses. This study was undertaken viewing more efficient either physical or chemical methods for the control of M. polymorpha. Two experiments were conducted under greenhouse conditions. In the first acetic acid (10, 20, and 40% of concentration), oxygenated water (50 and 100%) and the herbicides glyphosate (1,680 g AI ha) and fomesafen (375 g AI ha-1 ) were applied to the seedlings. In the second, the treatments consisted of soil previously submitted to a temperature of 105 °C for 48 hours, soil submitted to solarization in black plastic and in transparent plastic bags for 30 days, preemergence application of diuron (1,750 g AI ha-1 ) and trifluralina (1,575 g AI ha-1 ). The visual evaluations of the methods were performed 7, 14, 21, and 28 days after the application (DAA) and at 60 and 120 DAA, respectively, for the first and the second experiment. Only diuron and trifluralina resulted in a 100% control of M. polymorpha 120 DAA.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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O sistema cultivo mínimo, por possibilitar pouca movimentação de solo, menor número de operações agrícolas sem incorporação dos resíduos vegetais, apresenta vantagens em razão do menor custo de preparo e da redução das perdas de solo e água. No ano agrícola de 2006/2007, na Fazenda de Ensino e Pesquisa da Faculdade de Engenharia de Ilha Solteira, SP, Brasil - FEIS/UNESP, situada nas condições do Cerrado Brasileiro, objetivou-se analisar a produtividade de massa de matéria seca da consorciação de forragem (guandu+milheto) (MSF), em função de atributos físicos do solo, tais como resistência à penetração (RP), umidade gravimétrica (UG), umidade volumétrica (UV) e densidade do solo (DS) nas profundidades de 0,0-0,10 m; 0,10-0,20 m e 0,20-0,30 m. Para tanto, foi instalado um ensaio, contendo 117 pontos amostrais, em um Latossolo Vermelho distroférrico, sob pivô central, numa área experimental de 1600 m² sob cultivo mínimo. A análise estatística constou de análise descritiva inicial dos atributos e análise das correlações lineares simples entre eles, e, finalmente, de análise geoestatística. Do ponto de vista da correlação espacial, o atributo que mais bem explica a produtividade de massa de matéria seca da consorciação é a densidade do solo na camada de 0,20-0,30 m, com uma correlação inversa, indicando que as espécies se desenvolvem bem em solos adensados.