986 resultados para Davidson, Lucretia Maria, 1808-1825.
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The aim of this study was to evaluate the influence of different periods of rainfall that occurred after the application of the imazapyr herbicide on the control efficiency of Pistia stratiotes and Eichhornia crassipes. We studied 10 mm rainfall, applied for 5' at different time periods (0h, 2h, 4h, 6h, 8h, 12h, 24h, not simulated rainfall) after the application of imazapyr formulation Arsenal NA, 250 g ai ha -1 (1.0 L cp ha -1). The experiment had completely randomized design with four replications. Plants were evaluated at 7, 14, 21, 28 and 35 days after application (DAA), and the results submitted to analysis of variance by F test and treatment means compared by Tukey's test (p <0. 05). The occurrence of rainfall up to 6 hours after herbicide application, plants of P. stratiotes, negatively affected its efficiency and control; rainfall intervals over 8 hours had no effect in control. The occurrence of rainfall at all time intervals did not affect the control of E. crassipes plants.
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The aim of this work was to evaluate the control in pre-emergence of the weeds brachiaria grass (Brachiaria decumbens) and goosegrass (Eleusine indica) in different depths in the ground, for the oxyfluorfen and isoxaflutole herbicides, applied in pre-emergence condition and submitted of different rain blades. The experimental design was entirely at random, with four repetitions. Each set was consisted of plastic vases with substratum capacity of 4L, filled with arenaceous ground, increased of brachiaria grass and goosegrass seeds in the depths: 0,5; 1,0; 3,0; 6,0 and 9,0 cm. Doses of 37,5 g a.i. ha -1 of isoxaflutole and 720 g a.i. ha -1 of oxyfluorfen were used. The rain blades was 5, 10 and 20 mm applied with a stationary rain simulator, beyond a treatment without rain. Visual evaluations of control at 7 and 14 days had been carried through after application of the herbicides, counting of germinated plants and dry biomass of plants without application. The development of both weeds was inhibited by herbicides, reaching 100% of control, in all depth levels. The different rain blades had not influenced the control of the weeds. In the biggest depth of sowing (9,0 cm), the emergence was above 45% to B. decumbens and 36% to E. indica in treatments without herbicides application.
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Management systems affect soil structure, causing changes in porosity that can influence water infiltration into the soil. This study aimed to evaluate the effect of different management systems on the porosity and water infiltration in Distroferric Red Nitosol with clay texture. The management systems were: conventional with disc plow + two soft harrowing, conventional with heavy disc harrow + two soft harrowing, no tillage and fallow. The following attributes: porosity, pore shape and water infiltration velocity into the soil were determined. Management systems such as no-tillage, conventional with disc plow and heavy disc harrow, and fallow modify the porosity and the shape of pores of a Distroferric Red Nitosol, influencing water infiltration, which was favored in no-tillage for the greater presence of elongated pores.
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The study aimed to assess the moisture and density of the soil, the amount of water stored in the profile, and the average soil's porosity with Eucalyptus grandis reforestation, compared to bare soil. The study areas are located in the Paulista region, in São Paulo, Brazil. The samples were collected in layers of 0, 20, 40, 60, 100 and 300 cm, in the months of April, June, August and October 2008. The results show that the density is lower and the porosity is higher in Eucalyptus forest soil compared to bare soil, due to the higher content of organic matter in forest leaf litter. Furthermore, the forest soil has a lower amount of water stored in profile than the bare soil without vegetation.
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Pós-graduação em Artes - IA
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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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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em História - FCHS
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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)