1000 resultados para Vegetação de cobertura
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The success in weed control by using straw depends on the management time, straw quality and quantity. The objective of this research was to evaluate the suppressor effect of black-oats and millet straw cover on the incidence of weeds and on the productivity of the soybean crop. The experiment was carried out during the years 2006 and 2007, in an area from the Farm of Education, Research and Production of FCAV-UNESP, Jaboticabal Campus, in a completely randomized block design, with four replications. Treatments consisted of different types of black oats and pearl millet straw management before soybean seeding (without management, obtained by machine cut, desiccated using glyphosate desiccation and with paraquat) and different periods of straw deposition (0, 15, 30 e 60 days before soybean seeding). The weed population and the characteristics of soybean growth and production were evaluated. The deposition of black oats and pearl millet straw provided reductions in weed density and dry mass, and this effect was more effective when the deposition occurred until 15 days prior to soybean seeding. The suppressor effect of black oats straw was more pronounced than that of pearl millet straw, regardless of the drying method, although the millet had a greater dry matter production. No significant differences were found between the drying methods and the straw effectiveness.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Culture options for the autumn-winter season are a major problem for production systems under low rainfall. The aim of this study was to evaluate the effect of the sowing season on dry matter yield, nutrient content of the shoot and soil covering percentage of coverage plants on the soil on the intercrop: grain sorghum, rattlepods, pearl millet brachiaria grass and an area with weeds (fallow). The experiment was conducted under field conditions on an Oxisol (Haplustox), clay texture, in Selvíria, Mato Grosso do Sul, Brazil. The experimental design was a randomized block design with eight replications, two sowing seasons and five coverage treatments. When the sorghum culture of the first sowing season reached the harvest stage, the dry matter yield on the other treatments was evaluated. Results showed that sowing in March results in higher dry mass yield and higher soil coverage percentage in the studied species. In the first sowing season, Brachiaria brizantha presents higher dry matter yield and macronutrients extraction.
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This work aims to analyze the land use evolution in the city of Santa Cruz do Rio Pardo - SP through supervised classification of Landsat-5 TM satellite images according to the maximum likelihood (Maxlike), as well as verifying the mapping accuracy through Kappa index, comparing NDVI and SAVI vegetation indexes in different adjustment factors for the canopy substrate and determining the vegetal coverage percentage in all methods used on 2007, May 26 th; 2009, January 7 th and 2009, April 29 th. The Maxlike classification showed several spatial changes in land use over the study period. The most appropriated vegetation indexes were NDVI and SAVI - 0,25 factor, which showed similar values of vegetal coverage percentage, but discrepant from the inferred value for Maxlike classification.
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Besides increasing productivity, nitrogen fertilization may have positives effects on seed physiological quality. The objective of this study was to evaluate the effect of different forms and levels of urea in top dressing fertilization on the physiological quality of wheat seed genotypes. Seeds of three wheat genotypes (BRS 208, BRS Pardela and IWT 04008) were evaluated for four levels of nitrogen fertilization (0, 40, 80 and 120 kg.ha-1) in three forms of urea (conventional urea, urea with urease inhibitor and protected urea). The nitrogen fertilization was applied during tillering, 20 days after emergence. The seed nitrogen content, 1000 seed mass, germination and vigor (germination first count, cold test, seedling emergence in the field, dry weight of seedlings, accelerated aging and electrical conductivity) were evaluated. The IWT 04008 line and the cultivar BRS Pardela had seeds with a higher physiological quality than those of the cultivar BRS 208. The forms of urea and levels of nitrogen in topdressing did not affect seed physiological quality of the different wheat genotypes.
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The use of cover crops in the soil causes changes in soil attributes influencing in a series of hydro-physical processes, which also modify the ability of soil to support the many activities that it is intended. Thus, the objective of this study was to evaluate the effect of cover crops on physical attributes of the soil. For this, an experiment was carried out on a Typic Hapludox, Jaboticabal State, Brazil, using cover crops of millet, sunn hemp, jack bean, lab-lab and black velvet bean in no-tillage and fallow area (spontaneous vegetation). The characteristics evaluated were the bulk density, macroporosity, microporosity, total porosity, aggregate stability, penetration resistance and organic matter. The incorporation of cover crops has proved to be a beneficial practice for the physical attributes of the soil, allowing a greater aggregate stability compared to fallow in the depth of 0-0.05 m. All cover crops presented values of soil penetration resistance below the critical value of 2 MPa.
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The fiber quality, productivity and favorable climate are considered key points for the development of the cotton crop in the Brazilian Cerrado. This study aimed to evaluate the effect of cover crops and N application in presowing on the cotton crop growth and yield. The experimental design was randomized blocks, consisting of a - three cover crops (radish, white oat and black oat) implanted during the winter period, b - four nitrogen levels (0, 30, 60 and 90 kg ha-1 of N) applied to the millet residues and before cotton sowing. In April 2008, evaluations were realized of plant development and also harvesting was performed of experimental plots of cotton plants. The results showed that the radish provides increased length of branches and cotton bolls of cotton crop, without yield increase, and the use of increasing doses of N up to 90 kg ha-1 decreased the amount of carimã per plant, increasing the number of reproductive branches and cotton yield.
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Although there are recommendations for the fertilization of commercial squash crops, studies which connect the effect of topdressing potassium fertilization and yield are still rare. Thus, this study aimed at evaluating topdressing potassium doses on squash (Mirian hybrid) yield, in an experimental farm of the Universidade Estadual Paulista Júlio de Mesquita Filho, in São Manuel, São Paulo State, Brazil. The experimental design was randomized blocks, with five treatments (0.0 kg ha-1, 50.0 kg ha-1, 100.0 kg ha-1, 200.0 kg ha-1 and 400.0 kg ha-1 of K2O) and six replications. Plant growth parameters, yield and fruit quality were evaluated. After harvesting, plant (leaves + stem) and soil macronutrients were submitted to chemical analysis and data to variance and regression analysis. It was concluded that the highest yield resulted from the topdressing dose of 199.0 kg ha-1 of K2O. A reduction in calcium and magnesium contents in the plant canopy and a higher K+ content in the soil were observed for increasing K2O levels.
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The amount and timing of nitrogen application can favor seed quality, such as increasing protein content, which is an important constituent for embryo development. The objective of this study was to evaluate the physiological quality of sweet corn seeds collected from plants cultivated with different dosages and timings of nitrogen top-dressing applications. Seeds of the BR 400 variety (Super Sweet) were used obtained from plants submitted to dosages of 0, 40, 80 and 120kg ha -1 of N in two top-dressing applications (vegetative and reproductive stages). The weight of 100 grains, germination, first count of germination test, dry weight of normal seedlings from the germination test, seedling growth, cold test, accelerated aging, tetrazolium vigor and electric conductivity and emergency speed rate were determined. Data was submitted to an analysis of variance using the F-test at the 5% level and second degree regression analysis. The dosage and time of application of nitrogen top-dressing did not affect seed weight or the germination of sweet corn seeds. An increase of the N top-dressing dosage, applied in the vegetative stage reduced the length of the aerial part, the root and the whole seedling.