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Porto Alegre, Brazil

Monteiro P.F.C.,University of Sao Paulo | Monteiro P.F.C.,Federal University of Rio Grande do Sul | Filho R.A.,University of Sao Paulo | Xavier A.C.,Alto Universitario | Monteiro R.O.C.,University of Sao Paulo
Scientia Agricola | Year: 2012

Recently high spectral resolution sensors have been developed, which allow new and more advanced applications in agriculture. Motivated by the increasing importance of hyperspectral remote sensing data, the need for research is important to define optimal wavebands to estimate biophysical parameters of crop. The use of narrow band vegetation indices (VI) derived from hyperspectral measurements acquired by a field spectrometer was evaluated to estimate bean (Phaseolus vulgaris L.) grain yield, plant height and leaf area index (LAI). Field canopy reflectance measurements were acquired at six bean growth stages over 48 plots with four water levels (179.5; 256.5; 357.5 and 406.2 mm) and tree nitrogen rates (0; 80 and 160 kg ha -1) and four replicates. The following VI was analyzed: OSNBR (optimum simple narrow-band reflectivity); NB_NDVI (narrow-band normalized difference vegetation index) and NDVI (normalized difference index). The vegetation indices investigated (OSNBR, NB_NDVI and NDVI) were efficient to estimate LAI, plant height and grain yield. During all crop development, the best correlations between biophysical variables and spectral variables were observed on V4 (the third trifoliolate leaves were unfolded in 50 % of plants) and R6 (plants developed first flowers in 50 % of plants) stages, according to the variable analyzed. Source

Formigoni M. H.,Alto Universitario | Xavier A.C.,Federal University of Espirito Santo | de Souza Lima J.S.,Federal University of Espirito Santo
Ciencia Florestal | Year: 2011

The Brazilian Northeast (NEB) region presents different vegetation types that are important to maintain this ecosystem. With remote sensing techniques it is possible to analyze variations in vegetation community and alterations in vegetation phenology. The main objective of this work is to evaluate the temporal behavior of the Enhanced Vegetation Index (EVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) of different vegetation types in the NEB over the period ranging from February/2000 to July/2006. The study area was a 1,800 km long transect at latitude -6°41'24' enclosed at the NEB region. A map of Brazil (1:5,000,000 scale, from Brazilian Institute of Geography and Statistics, IBGE) was used to characterize the vegetation types. A total of 144 cloud-free EVI images with spatial resolution of 250 m were acquired from National Aeronautics and Space Administration (NASA). The results showed that: i) EVI data were sensible to the vegetation types; ii) amazon vegetation presented lesser variation in the multi-temporal EVI, however with greater values; iii) Caatinga vegetation presented greater EVI values variation. Source

Duffles P.,Federal University of Rio de Janeiro | Duffles P.,Alto Universitario | Trouw R.A.J.,Federal University of Rio de Janeiro | Mendes J.C.,Federal University of Rio de Janeiro | And 2 more authors.
Precambrian Research | Year: 2016

The Embu Complex crops out in the southeastern part of São Paulo state in Brazil and consists mainly of Neoproterozoic metasedimentary rocks belonging to the interference zone between the Brasilia and Ribeira fold belts. We present U-Pb ages (LA-IPCMS) supported by cathodoluminescence images for detrital zircon from these rocks in order to constrain the formation and evolution of the source area of this complex. In this paper we choose to individualize within the Embu Complex a Paleoproterozoic basement, a metasedimentary sequence, the Embu Sequence, and Neoproterozoic intrusive bodies, now largely orthogneisses. Six distinct rock types were recognized in the Embu Sequence: biotite gneiss, biotite schist, quartzite, amphibolite, calc-silicate rock and talc schist. The sequence is strongly deformed by several deformation phases and metamorphosed into amphibolite facies. An important shear zone, the Buquira Shear zone, separates the Embu Complex from the Socorro-Guaxupé Nappe, to the north, considered to be part of the upper plate of the southern Brasília belt collision. However, our mapping showed that the shear zone cuts obliquely into the Embu Complex, diminishing considerably its regional importance. Three samples were separated for dating, a schist north of the shear zone and two quartzites south of the shear zone. The results show that the ages of detrital zircon of these samples are mainly Paleoproterozoic, with a minor Archean component. The youngest igneous zircon grain from the schist produced an age of about 1000 Ma, indicating the maximum sedimentation age for the sequence. No significant difference appears between the samples north and south of the shear zone, reforcing the interpretation that this zone is only of local importance. Important metamorphic overgrowth of zircon in the age range 670-640 is present in all three samples; it is interpreted as related to the installment of a continental magmatic arc in the Socorro-Guaxupé Nappe and in the Embu Complex. A second metamorphic pulse between 621 and 599 Ma is only apparent in one sample. According to the literature this was the period of continental collision between the Paranapanema and São Francisco paleocontinents leading to the formation of the southern Brasília belt. Possibly the fact that the analyzed samples are localized some 30 km away from the suture, in the upper plate, explains that the increase in temperature during the collision in this area was insufficient to grow significant new zircon. A third metamorphic pulse with ages of 576-574 Ma, possibly related to collision in the Ribeira belt, is only detected in three analyses of metamorphic rims in the schist sample. Earlier reported ages of about 790 Ma, both for igneous crystallization and metamorphism in a more westerly part of the Embu Complex, are only recognized in one analysis of metamorphic overgrowth (794 ± 24 Ma) from the schist sample, and two probably hybrid analyses of 830 ± 19 Ma and 767 ± 14 Ma from the northern quartzite sample. It is concluded that the results show that the detritic zircon is probably derived from the Paranapanema Paleocontinent. © 2016 Elsevier B.V. Source

da Silva A.F.,Federal University of Espirito Santo | de Souza Lima J.S.,Alto Universitario | de Oliveira R.B.,Sao Paulo State University
Idesia | Year: 2010

There are many methods used to estimate values in places no sampled for construction of contours maps. The aim of this study was to use the methods of interpolation kriging, inverse of the square of the distance and polynomial in the representation of the spatial variability of the pH of the soil in the organic and conventional management in the culture of the coffee plantation. For that, irregular meshes were built for soil sampling in the depth of 0-0,10 meters, totaling 40 points sampling in each area. For gauging of the interpolation methods they were solitary 10% of the total of points, for each area. Initially, the data were appraised through the classic statistics (descriptive and exploratory) and spatial analysis. The method inverse square of the distance and kriging has low error in estimating dados. The method of kriging presented low variation around the average in different managements. Source

The aim of this paper was to evaluate economical viability and steers performance in grazing receiving supplements with increasing levels of crude protein in the rainy season and its correlation with the pasture ́s composition. The test animals were 21 not castrated steers supplemented with mineral supplement and multiple supplements with 20% and 40% of crude protein and heavy at the beginning and the end of the experiment, after being submitted to fasting from liquids and solids for 14 hours. For analysis of the economic viability was used the difference between the Total Revenue and Total Cost. The protein supplementation didn't influence of the animals performance in grazing. The average daily gain of animals was 0.849 kg. The content of crude protein in the cell wall was negatively correlated with animal performance, and the structural characteristics of the pasture just the mass of forage showed a strong and positive correlation. This activity in the studied period presented economic viability when considered return on capital of 8% a year. Source

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