1000 resultados para Brazilian poetry.


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The assessment of bacterial communities in soil gives insight into microbial behavior under prevailing environmental conditions. In this context, we assessed the composition of soil bacterial communities in a Brazilian sugarcane experimental field. The experimental design encompassed plots containing common sugarcane (variety SP80-1842) and its transgenic form (IMI-1 - imazapyr herbicide resistant). Plants were grown in such field plots in a completely randomized design with three treatments, which addressed the factors transgene and imazapyr herbicide application. Soil samples were taken at three developmental stages during plant growth and analyzed using 16S ribosomal RNA (rRNA)-based PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and clone libraries. PCR-DGGE fingerprints obtained for the total bacterial community and specific bacterial groups - Actinobacteria, Alphaproteobacteria and Betaproteobacteria - revealed that the structure of these assemblages did not differ over time and among treatments. Nevertheless, slight differences among 16S rRNA gene clone libraries constructed from each treatment could be observed at particular cut-off levels. Altogether, the libraries encompassed a total of eleven bacterial phyla and the candidate divisions TM7 and OP10. Clone sequences affiliated with the Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria were, in this order, most abundant. Accurate phylogenetic analyses were performed for the phyla Acidobacteria and Verrucomicrobia, revealing the structures of these groups, which are still poorly understood as to their importance for soil functioning and sustainability under agricultural practices.

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Nutrient dynamics in tropical soils sustaining forage grasses are still poorly understood. We conducted a study to evaluate the effect of combined N and S fertilizer rates on the growth of `Marandu` palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) Stapf], uptake of these elements from the soil by plants, soil organic matter concentration, soil pH, and the mineral and organic fractions of N and S in an Entisol. Combinations of five N rates (0, 100, 200, 300, and 400 g N m(-3)) with five S rates (0, 10, 20, 30, and 40 g S m(-3)) were evaluated in a partial 5 x 5 factorial in a pot experiment, with and without plants. Nitrogen and S were supplied as NH(4)NO(3) and CaSO(4)center dot 2H(2)O, respectively. The N addition in excess did not enhance the palisade grass production due to low plant-available Sin the soil. The supply of low rates of S with N greatly improved the overall N uptake efficiency by the forage plant. The contents of total N, NO(3)(-)-N, and NH(4)(+)-N in the soil varied with N rate and with N uptake by the plants. The association of palisade grass with S fertilization increased the ester-bonded S fraction in the soil. The results suggest that soil residual S could be a potential source of S for plants. Proper N and S fertilizer rates promoted increased grass production due to increased uptake of these nutrients and the dynamics of the organic N and S fractions and mineral fractions in this tropical soil.

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This paper investigates whether initiatives for sustainability certification of Brazilian ethanol can be expected to stimulate a change among producers toward more sustainable production - and, if so, what those changes would likely be. Connected to this, several questions are raised including whether producers might prefer to target other markets with less stringent demands, and if certification might lead to structural changes in the sector because producers who lack the capacity to meet the new requirements cannot remain competitive. The analysis of interviews with a diverse group of stakeholders under the guidance of the Technological Innovation Systems framework allowed us identify different actions taken by the Brazilian sugarcane ethanol sector in response to requirements of sustainability. The interviewees agreed that sustainability certification is an important element for the expansion of biofuel production in Brazil. Brazilian stakeholders have created a platform for more competitive sustainable production and have initiated relevant processes in response to the development connected to sustainability certification. Yet, the certification activities have had a limited impact in terms of the number of involved stakeholders. But interview responses indicate that the sector may adapt to new certification requirements rather than leave markets where such requirements become established. Structural changes can be expected if certification requirements as they exist in many initiatives are introduced in unflexible ways. The social importance of the ethanol industry is large in Brazil and some adjustments for certification may be required. The paper concludes by suggesting some actions for the industry. (C) 2010 Society of Chemical Industry and John Wiley & Sons, Ltd

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Mehlich-1, resin-HCO(3), and Pi tests were used to assess available P in an acid tropical Oxisol in Brazil treated with gypsum, which has been preferred over lime to ameliorate the Al toxicity in the subsoil. The soil was incubated in the laboratory at rates up to 75 g kg(-1) of phosphogypsum (PG) containing 0.3% total P, natural gypsum, or reagent-grade gypsum, and up to 100 mg P kg(-1) as triple superphosphate (TSP) or phosphate rock (PR). In the greenhouse, two consecutive maize crops were grown on the soil treated with 50 mg P kg(-1) of TSP and PG rates up to 75 g kg(-1). The results of the incubation study showed that Mehlich-P and Pi-P increased with increasing PG rate for the treatments of TSP, PR, and control. Resin-HCO(3) underestimated available P from TSP and PR because of the reaction between resin-HCO(3) and gypsum. Mehlich-1 overestimated available P from PR compared with TSP because of an excessive dissolution of PR by the strongly acidic Mehlich-1. Pi underestimated available P from PR in the treatments of natural and reagent-grade gypsum because of Ca common-ion effect from gypsum on depressing PR dissolution. The results in terms of the effect of PG on available P are similar in both incubation and greenhouse studies. Both Mehlich-P and Pi-P correlated well with P uptake by maize, whereas resin-P did not.

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Mangrove ecosystems are environments subject to substantial degradation by anthropogenic activities. Its location, in coastal area, interfacing the continents and the oceans makes it substantially important in the prospection for biotechnological applications. In this study, we assessed the diversity of culturable bacteria present over the seasons at two depths (0-10 and 30-40 cm) in a mangrove sediment and in a transect area from the land to the sea. In total, 238 bacteria were isolated, characterized by Amplified Ribosomal DNA Restriction Analysis (ARDRA) and further identified, by Fatty Acid Methyl Esther (FAME-MIDI), into the orders of Vibrionales, Actinomycetales and Bacillales. Also the ability of the isolates in producing economically important enzymes (amylases, proteases, esterases and lipases) was evaluated and the order Vibrionales was the main enzymatic source.

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The soil organic matter (SOM) extracted under different vegetation types from a Brazilian mangrove (Pai Matos Island, Sao Paulo State) and from three Spanish salt marshes (Betanzos Ria and Corrubedo Natural Parks, Galicia, and the Albufera Natural Park, Valencia) was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The chemical variation was larger in SOM from the Spanish marshes than in the SOM of the Brazilian mangroves, possibly because the marshes included sites with both tidal and nontidal variation, whereas the mangrove forest underwent just tidal variation. Thus, plant-derived organic matter was better preserved under permanently anoxic environments. Moreover, given the low number of studied profiles and sedimentary-vegetation sequences in both areas, depth trends remain unclear. The chemical data also allow distinction between the contributions of woody and nonwoody vegetation inputs. Soil organic matter decomposition was found to cause: (i) a decrease in lignin contents and a relative increase in aliphatics; (ii) an increase in short-chain aliphatics at the expense of longer ones; (iii) a loss of odd-over-even dominance in alkanes and alkenes; and (iv) an increase in microbial products, including proteins, sterols, short-chain fatty acids, and alkanes. Pyrolysis-gas chromatography/mass spectrometry is a useful tool to study the behavior and composition of SOM in wetland environments such as mangroves and salt marshes. Additional profiles need to be studied for each vegetation type, however, to improve the interpretability of the chemical data.

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Changes in soil sodicity-salinity parameters are one of the most characteristic alterations after treated sewage effluent (TSE) irrigation in agro-systems. Considering the importance of these parameters for agricultural management, as well as the economical value of sugarcane for Brazil, the present study aimed at evaluating effects on soil sodicity and salinity under tropical conditions over 16 months of TSE irrigation in a sugarcane plantation at Lins, Sao Paulo State, Brazil. Soil samplings were carried out in February 2005 (before planting), December 2005 (after 8 months of TSE irrigation) and September 2006 (after 16 months of TSE irrigation) following a complete block design with four treatments and four replicates. Treatments consisted of. (i) control, without TSE irrigation; (ii) T100, T150 and T200, with TSE irrigation supplying 100% (0% surplus, total of 2524 mm), 150% (50% surplus, total of 3832 mm) and 200% (100% surplus, total of 5092 mm) of crop water demand, respectively. Compared to initial soil conditions, at the end of the experiment increases of exchangeable sodium (from 2.4 to 5.9 mmol(c) kg(-1)), exchangeable sodium percentage (ESP) (from 8 to 18%), soluble Na (from 1.4 to 4.7 mmol L(-1)) and sodium adsorption ratio (SAR) of soil solution (from 3.6 to 12.6 (mmol were found in the soil profile (0-100 cm) as an average for the irrigated plots due to high SAR of TSE. Associated with the increments were mostly significant increases in clay dispersion rates at depths 0-10, 10-20 and 20-40 cm. Electrical conductivity (EC) of soil solution increased during the TSE irrigation period whereas at the end of the experiment, after short term discontinuation of irrigation and harvest, EC in the topsoil (0-10 and 10-20 cm) decreased compared to the previous samplings. Moreover, despite increasing sodicity over time mainly insignificant differences within the different irrigated treatments were found in December 2005 and September 2006. This suggests that independent of varying irrigation amounts the increasing soil sodicity over time were rather caused by the continuous use of TSE than by its quantity applied. Moreover, also plant productivity showed no significant differences within the TSE irrigated plots. The study indicates that monitoring as well as remediation of soil after TSE irrigation is required for a sustainable TSE use in order to maintain agricultural quality parameters. (C) 2008 Elsevier B.V. All rights reserved.

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The bacterial diversity present in sediments of a well-preserved mangrove in Ilha do Cardoso, located in the extreme south of So Paulo State coastline, Brazil, was assessed using culture-independent molecular approaches (denaturing gradient gel electrophoresis (DGGE) and analysis of 166 sequences from a clone library). The data revealed a bacterial community dominated by Alphaproteobacteria (40.36% of clones), Gammaproteobacteria (19.28% of clones) and Acidobacteria (27.71% of clones), while minor components of the assemblage were affiliated to Betaproteobacteria, Deltaproteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. The clustering and redundancy analysis (RDA) based on DGGE were used to determine factors that modulate the diversity of bacterial communities in mangroves, such as depth, seasonal fluctuations, and locations over a transect area from the sea to the land. Profiles of specific DGGE gels showed that both dominant (`universal` Bacteria and Alphaproteobacteria) and low-density bacterial communities (Betaproteobacteria and Actinobacteria) are responsive to shifts in environmental factors. The location within the mangrove was determinant for all fractions of the community studied, whereas season was significant for Bacteria, Alphaproteobacteria, and Betaproteobacteria and sample depth determined the diversity of Alphaproteobacteria and Actinobacteria.

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Information on nutritional requirement of some Brazilian farmed fish species, especially essential amino acids (EAA) requirements, is scarce. The estimation of amino acids requirements based on amino acid composition of fish is a fast and reliable alternative. Matrinxa, Brycon amazonicus, and curimbata, Prochilodus lineatus, are two important Brazilian fish with potential for aquaculture. The objective of the present study was to estimate amino acid requirements of these species and analyze similarities among amino acid composition of different fish species by cluster analysis. To estimate amino acid requirement, the following formula was used: amino acid requirement = [(amount of an individual amino acid in fish muscle tissue) x (average totalEAA requirement among channel catfish, Ictalurus punctatus, Nile tilapia, Oreochromis niloticus, and common carp, Cyprinus carpio)]/(average fish muscle totalEAA). Most values found lie within the range of requirements determined for other omnivorous fish species, in exception of leucine requirement estimated for both species, and arginine requirement estimated for matrinxa alone. Rather than writing off the need for regular dose-response assays under the ideal protein concept to determine EAA requirements of curimbata and matrinxa, results set solid base for the study of tropical species dietary amino acids requirements.

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A study was conducted in Brazil to identify factors affecting grazing distribution of yearling Nelore cross heifers and to evaluate the efficacy of placement of a salt-mineral mix away from water to improve uniformity of grazing. Two pastures (25 ha and 42 ha) were evaluated for four 15-d sessions. Mineral mix was placed 590 m to 780 m from water during two sessions and at water for two sessions. Stubble heights were measured at the beginning and end of each session in 1-ha subunits of each pasture. Cattle locations were recorded oil clay 13 and 14 of each session by horseback observers. Heifers avoided areas with a preponderance of forbs and taller grass (P < 0.001). For the first 15 days of the study cattle avoided subunits farther from water. Thereafter, horizontal distance from water had no affect on grazing use (P > 0.10). Stubble height reduction was more uniform (P < 0.05) when the mineral mix was Lit water compared to away from water. In contrast, heifers spent less time farther from water when Mineral mix was placed at water (P = 0.02) based Oil Visual observations. Strategic placement of a salt-mineral mix away from water does not appear to be a reliable tool to improve cattle grazing distribution in humid tropical pastures from 25 ha to 45 ha in size.

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The DSSAT/CANEGRO model was parameterized and its predictions evaluated using data from five sugarcane (Sacchetrum spp.) experiments conducted in southern Brazil. The data used are from two of the most important Brazilian cultivars. Some parameters whose values were either directly measured or considered to be well known were not adjusted. Ten of the 20 parameters were optimized using a Generalized Likelihood Uncertainty Estimation (GLUE) algorithm using the leave-one-out cross-validation technique. Model predictions were evaluated using measured data of leaf area index (LA!), stalk and aerial dry mass, sucrose content, and soil water content, using bias, root mean squared error (RMSE), modeling efficiency (Eff), correlation coefficient, and agreement index. The Decision Support System for Agrotechnology Transfer (DSSAT)/CANEGRO model simulated the sugarcane crop in southern Brazil well, using the parameterization reported here. The soil water content predictions were better for rainfed (mean RMSE = 0.122mm) than for irrigated treatment (mean RMSE = 0.214mm). Predictions were best for aerial dry mass (Eff = 0.850), followed by stalk dry mass (Eff = 0.765) and then sucrose mass (Eff = 0.170). Number of green leaves showed the worst fit (Eff = -2.300). The cross-validation technique permits using multiple datasets that would have limited use if used independently because of the heterogeneity of measures and measurement strategies.

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There is a widespread view that forest plantations with exotic species are green deserts, unable to sustain biodiversity. Few studies have demonstrated, however, that planted stands of exotic trees have a greater negative effect on the plant diversity of savanna vegetation. We compared the native woody flora under four stands of slash pine of about 45 years old with four stands where the previously existing native Cerrado vegetation was preserved and protected from disturbances for the same period, has changed into dense vegetation - the ""cerradao"", at Assis municipality, Sao Paulo State, Brazil. Aiming at understanding the potential ecological filters driving these communities, we assessed air and soil humidity, light availability and classified the native species on the basis of shade tolerance, dispersal syndrome and biomes in which they occur (Atlantic Forest or Cerrado). We recorded an average of 70 (+/- 13) species under pine stands and 54 (+/- 16) species in cerradao. Of the total of 136 species recorded, 78 occurred in both habitats, eight were exclusive to the ""cerradao"" (shade tolerant and also occurring in forest ecosystems) and 18 were recorded only under pine stands (82% heliophytic, exclusive to the Cerrado biome). Among the functional attributes and abiotic variables analyzed, only light availability explained the floristic differences found. Since richness was higher under pine, we refuted the hypothesis that exotic species constrain the establishment of the native species richness in the understory. On the other hand, the dark environment under the closed-canopy of the ""cerradao"" acts as a filter inhibiting the establishment of typical Cerrado species. Since pine stands, if managed in long cycle, maintain a reasonable pool of Cerrado endemic species in the understory pine plantations may be a good starting point for savanna restoration. (C) 2011 Elsevier B.V. All rights reserved.

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Brazilian agriculture covers about one-third of the land area and is expected to expand further We assessed the compliance of present Brazilian agriculture with environmental legislation and identified challenges for agricultural development connected to this legislation We found (i) minor illegal land use in protected areas under public administration, (ii) a large deficit in legal reserves and protected riparian zones on private farmland, and large areas of unprotected natural vegetation in regions experiencing agriculture expansion Achieving full compliance with the environmental laws as they presently stand would require drastic changes in agricultural land use, where large agricultural areas are taken out of production and converted back to natural vegetation The outcome of a full compliance with environmental legislation might not be satisfactory due to leakage, where pristine unprotected areas become converted to compensate for lost production as current agricultural areas are reconverted to protected natural vegetation. Realizing the desired protection of biodiversity and natural vegetation, while expanding agriculture to meet food and biofuel demand, may require a new approach to environmental protection New legal and regulatory instruments and the establishment of alternative development models should be considered

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The tree species Guarea guidonea (Meliaceae) belongs to a predominantly tropical family, being largely found in natural or anthropic forest fragments within the Brazilian Atlantic Forest. Aiming to develop future studies on the genetic structure of plant species from forests fragments, eleven microsatellite markers were developed for Guarea guidonia, based on the analysis of 45 individuals from natural populations of three different fragments within the forest-anthropic edge, interior fragment and natural edge. Only eight loci showed to be polymorphic and the number of alleles ranged from two to four (mean of 2.50). All populations showed almost the same level of genetic diversity (mean H(e) = 0.3775). These loci will be useful for population genetics studies on Guarea guidonea, providing information for the conservation and management of this species.

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Shoot elongation of Hancornia speciosa, an endangered tree from the Brazilian savannah ""Cerrado"", is very slow, thus limiting nursery production of plants. Gibberellins (GAs) A(1), A(3), and A(5), and two inhibitors of GA biosynthesis, trinexapac-ethyl and ancymidol were applied to shoots of Hancornia seedlings. GA(1) and GA(3) significantly stimulated shoot elongation, while GA(5) had no significant effect. Trinexapac-ethyl and ancymidol, both at 100 A mu g per seedling, inhibited shoot elongation up to 45 days after treatment, though the effect was statistically significant only for ancymidol. Somewhat surprisingly, exogenous GA(3) more effectively stimulated shoot elongation in SD-grown plants, than in LD-grown plants. The results from exogenous application of GAs and inhibitors of GA biosynthesis imply that Hancornia shoot growth is controlled by GAs, and that level of endogenous growth-active GAs is likely to be the limiting factor for shoot elongation in Hancornia. Application of GAs thus offer a practical method for nursery production of Hancornia seedlings for outplanting into the field.