Non-labile plant C contributes to long-lasting macroaggregation of an Oxisol

Decomposition of plant material influences soil aggregation dynamics in ways that are still poorly understood, especially for Oxisols, in which oxides are believed to play a dominant role. In an incubation experiment, we investigated (i) the effect of plant material addition from selected monocot and dicot species on soil organic C (SOC), carbohydrate composition, fungal and total microbial biomass, and aggregation of an Oxisol; and (ii) the relationship among these properties and C mineralization patterns. The experiment was carried out at 25 °C for 180 d after addition of 11 plant materials (4 g C kg-1 soil) and a control (no plant material added). Mineralization of C during the incubation was described considering two pools of C (labile and non-labile) using a first-order plus linear fitting. Compared to the control, corn materials showed larger pentose input, greater mineralization rates for the non-labile C pool (k), greater soil pentose content (xylose + arabinose) and larger mean weight diameter of soil water-stable aggregates at 180 d of incubation. These effects were independent of changes in SOC content, suggesting that total C accrual and macroaggregation may be decoupled processes in this Oxisol. Our results support the hypothesis that the non-labile plant C pool contributes to the long-lasting stability of macroaggregates of this Oxisol and that this effect is mediated by plant and soil pentoses. We propose that plant pentose content and the decomposition rate of the slow pool (k) are useful parameters for the prediction of plant effects on aggregation dynamics of Oxisols and the selection of soil conservation practices. © 2012.

Sequential Sampling Plan for Tenuipalpus heveae Baker (Acari: Tenuipalpidae) on Rubber Tree

The objective of the present study was to develop a sequential sampling plan for the decision-making process to control Tenuipalpus heveae Baker (Acari: Tenuipalpidae), an important pest of the rubber tree crop. The experimental area was represented by 1,000 plants of the RRIM 600 clone divided in 100 plots with 10 plants each. Leaves were collected and the number of mites determined under laboratory conditions. The sequential sampling plan was developed in accordance with the Sequential Test Likelihood Ratio. The value 0.10 was pre-established for α and β representing type I and type II errors, respectively. The level of control adopted was six mites per 12 cm2. The operating characteristic curve and the curve of maximum expected sample were determined. Two lines were generated: the upper one, when the condition for chemical control is recommended (S1 = 23.3080 + 2.1972); and the lower, when chemical control is not recommended (S0 = -23.3080 + 2.1972). Sample size for the decision-making process to control T. heveae requires 6 to 18 plants. © 2013 Sociedade Entomológica do Brasil.

Time in the stair-climbing test as a predictor of thoracotomy postoperative complications

Objectives: The stair-climbing test as measured in meters or number of steps has been proposed to predict the risk of postoperative complications. The study objective was to determine whether the stair-climbing time can predict the risk of postoperative complications. Methods: Patients aged more than 18 years with a recommendation of thoracotomy for lung resection were included in the study. Spirometry was performed according to the criteria by the American Thoracic Society. The stair-climbing test was performed on shaded stairs with a total of 12.16 m in height, and the stair-climbing time in seconds elapsed during the climb of the total height was measured. The accuracy test was applied to obtain stair-climbing time predictive values, and the receiver operating characteristic curve was calculated. Variables were tested for association with postoperative cardiopulmonary complications using the Student t test for independent populations, the Mann-Whitney test, and the chi-square or Fisher exact test. Logistic regression analysis was performed. Results: Ninety-eight patients were evaluated. Of these, 27 showed postoperative complications. Differences were found between the groups for age and attributes obtained from the stair-climbing test. The cutoff point for stair-climbing time obtained from the receiver operating characteristic curve was 37.5 seconds. No differences were found between the groups for forced expiratory volume in 1 second. In the logistic regression, stair-climbing time was the only variable associated with postoperative complications, suggesting that the risk of postoperative complications increases with increased stair-climbing time. Conclusions: The only variable showing association with complications, according to multivariate analysis, was stair-climbing time. © 2013 by The American Association for Thoracic Surgery.

Resting heart rate: Its correlations and potential for screening metabolic dysfunctions in adolescents

Background: In pediatric populations, the use of resting heart rate as a health index remains unclear, mainly in epidemiological settings. The aims of this study were to analyze the impact of resting heart rate on screening dyslipidemia and high blood glucose and also to identify its significance in pediatric populations.Methods: The sample was composed of 971 randomly selected adolescents aged 11 to 17 years (410 boys and 561 girls). Resting heart rate was measured with oscillometric devices using two types of cuffs according to the arm circumference. Biochemical parameters triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and glucose were measured. Body fatness, sleep, smoking, alcohol consumption and cardiorespiratory fitness were analyzed.Results: Resting heart rate was positively related to higher sleep quality (β = 0.005, p = 0.039) and negatively related to cardiorespiratory fitness (β = -0.207, p = 0.001). The receiver operating characteristic curve indicated significant potential for resting heart rate in the screening of adolescents at increased values of fasting glucose (area under curve = 0.611 ± 0.039 [0.534 - 0.688]) and triglycerides (area under curve = 0.618 ± 0.044 [0.531 - 0.705]).Conclusion: High resting heart rate constitutes a significant and independent risk related to dyslipidemia and high blood glucose in pediatric populations. Sleep and cardiorespiratory fitness are two important determinants of the resting heart rate. © 2013 Fernandes et al.; licensee BioMed Central Ltd.

Sistemas de manejo e atributos físico-hídricos de um Latossolo Vermelho cultivado com milho

The purpose of this experiment was to evaluate the hydro-physical attributes of the Red Oxisol cultivated with maize in Jaboticabal, São Paulo State, Brazil, under different systems of use and periods of adoption of managements. The experiment was arranged in a completely randomized design with split-plot arrangement, with six replications and the treatments were: six years of no-tillage system (SPD6), eight years of no-tillage system (SPD8), ten years of no-tillage system (SPD10), conventional tillage system (SPC) and an adjacent area of native forest (NF). The soil penetration resistance (PR), density, macroporosity, microporosity of the soil in layers of 0-0.05; 0.05-0.10 and 0.10-0.20 m, and the saturated hydraulic conductivity (Kθ) in 0.15 m depth were evaluated. It was found that the PR conditions were favorable for the cultivation to 0.20 m, indicating a structure preserved even after soil chiseling. Furthermore, the Kθ in the soil showed similar behavior between SPC and periods of SPD, although this was shown in a part of maize cycle, macroporosity values near 0.10 m3 m-3 and soil water tensions near 0.09 MPa.

Análise das tensões de água no solo cultivado com morangueiro sob poda

Strawberry yield and quality was evaluated after drastic pruning (second cycle), under different soil water tensions, drip irrigation. The experiment was conducted on beds at a greenhouse, located at Engineering Department, Federal University of Lavras (UFLA), from April to December of 2010. An experimental design was in randomized blocks with three replicates. The treatments were composed of six different soil water tension, 15, 25, 35, 45, 55 e 70 kPa. Results obtained allowed to verify that to higher values of: total and commercial fresh weight of fruits per plant, total and commercial number fruits per plant and total and commercial yield, it is necessary to irrigate when soil water tension gets approximately to 15 kPa, at 0.15 m deep. Commercial average fruit mass and noncommercial fresh weight of fruits per plant, were not reduced under different soil water tensions applied.

Variação entre a lâmina de irrigação aplicada e armazenada no solo sob condições de irrigação com baixa uniformidade de distribuição de água

In sprinkler irrigation is important to have a good uniformity of application so that the water in the root zone does not show areas with little available water while others have percolating beyond the plant roots, even though the soil allows a lateral redistribution of water. A usual way to obtain the uniformity of irrigation is by measures of dispersion. The aim of this work was to evaluate the uniformity of water stored in a sand soil before and after non uniformity depth irrigation applied from one sprinkler, as well the variation of storage in a 0-0,45 m layer soil using a neutron probe. The statistical design was completely randomized, and for the variable Christiansen uniformity coefficient modified (CUCHH) were 10 treatments (the irrigation depth, 8 intervals of readings storage, more the existing one before irrigation added to the irrigation depth). For the variable soil water, the treatments were the same, excepting the irrigation depth. Despite the low surface uniformity (16.3%), there was not significantly difference between the storage uniformity before, after irrigation and the potential, however there was from these to the surface uniformity. From de irrigation depth, 15.3 mm, only 6.1 mm remained in the layer from 0 to 0.45 m. There was not significantly difference between the water stored in the soil before and after irrigation within a period of up to 134 hours, being the increase in storage due to irrigation was just 11.7%.

Instantaneously measured traits may detect non-plastic ecophysiological performances in response to drought, explaining distributions of Styrax species in the Cerrado

We analyzed the differences between irrigated and non-irrigated plants of three congeneric Styrax species that present distinct distribution patterns in the physiognomies of the Cerrado vegetation in Brazil. Styrax ferrugineus showed a stomatal conductance (gs) unresponsive to soil water deficit in potted plants. This may explain the high gas exchange and photochemical efficiency found in this species, which is well adapted to the Cerrado sensu stricto (s. str.), a savanna-type vegetation. S. camporum, which is widely distributed in the Cerrado sensu lato (s. l.) areas, was the only species that exhibited increased intrinsic water use efficiency on the days of maximum water deficit. This result distinguishes S. camporum from S. pohlii, which is a forest species, since the gs of both species decreased during the days of maximum water stress. In contrast to other studies, we propose that instantaneously measured traits, such as leaf gas exchange rates and chlorophyll fluorescence, may be used to detect non-plastic performances in response to environmental stress, helping explain distinct geographical distributions of congeneric species in the Cerrado vegetation. © 2013 Springer-Verlag Berlin Heidelberg.

Study of the threshold line between macroscopic and bulk behaviors for homogeneous type II superconductors

In this work we solved the time dependent Ginzburg-Landau equations to simulate homogeneous superconducting samples with square geometry for several lateral sizes. As a result of such simulations we notice that in the Meissner state, when the vortices do not penetrate the superconductor, the response of small samples are not coincident with that expected for the bulk ones, i.e., 4. πM=. -. H. Thus, we focused our analyzes on the way which the M(. H) curves approximate from the characteristic curve of bulk superconductors. With such study, we built a diagram of the size of the sample as a function of the temperature which indicates a threshold line between macroscopic and bulk behaviors. © 2013 Elsevier B.V.

Efeitos fisiológicos da piraclostrobina em plantas de feijão (Phaseolus vulgaris L.) condicionado sob diferentes tensões de água no solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morfo-anatomia de raízes tuberosas de mandioca (Manihot esculenta Crantz) cultivar IAC 576-70 em diferentes preparos do solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resposta de plantas de cobertura a doses de silício e estresse hídrico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Toxicidade aguda e risco ecotoxicológico do fipronil para o guarú (Poecilia reticulata) e dissipação no ambiente aquático

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação de ácido abscísico e respostas metabólicas em espécies congenéricas de savana e mata do cerrado paulista

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Desempenho ecofisiológico de Styrax ferrugineus, S. camporum E. S. pohlii (Styraceae), submetidos à deficiência híbrida em sistema semi controlado

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