Soil density evaluated by spectral reflectance as an evidence of compaction effects

Soil compaction, reflected by high bulk density, is an environmental degradation process and new technologies are being developed for its detection. Despite the proven efficiency of remote sensing, it has not been widely used for soil density. Our objective was to evaluate the density of two soils: a Typic Quartzpisament (TQ) and a Rhodic Paleudalf (RP), using spectral reflectance obtained by a laboratory spectroradiometer between 450 and 2500 nm. Undisturbed samples were taken at two depths (0-20 and 60-80 cm), and were artificially compacted. Spectral data, obtained before and after compaction, were compared for both wet and dried compacted samples. Results demonstrated that soil density was greater in RP than in TQ at both depths due to its clayey texture. Spectral data detected high density (compacted) from low density (non-compacted) clayey soils under both wet and dry conditions. The detection of density in sandy soils by spectral reflectance was not possible. The intensity of spectral reflectance of high soil bulk density (compacted) samples was higher than for low density (non-compacted) soils due to changes in soil structure and porosity. Dry samples with high bulk density showed differences in the spectral intensity, but not in the absorption features. Wet samples in equal condition had statistically higher reflectance intensity than that of the low soil bulk density (non-compacted), and absorption differences at 1920 nm, which was due to the altered position of the water molecules. Soil line and spectral reflectance used together could detect soil bulk density variations for the clay soil. This technique could assist in the detection of high soil density in the laboratory by providing new soil information.

Surface Liming and Zinc Availability in a Long-Term Experiment under No-Till System

No-till (NT) system with crop rotation is one of the most effective strategies to improve agricultural sustainability in tropical and subtropical regions. To control soil acidity in NT, lime is broadcast on the surface without incorporation. The increase in soil pH due to surface liming may decrease zinc (Zn) availability and its uptake by crops. A field experiment was performed in Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate Zn bioavailability in a NT system after surface liming and re-liming. Dolomitic lime was surface applied on the main plots in July 1993 at the rates of 0, 2, 4, and 6 Mg ha-1. In June 2000, the main plots were divided in two subplots to study of the effect of surface re-liming at the rates of 0 and 3 Mg ha-1. The cropping sequence was soybean [Glycine max (L.) Merrill] (2001-2 and 2002-3), wheat (Triticum aestivum L.) (2003), soybean (2003-4), corn (Zea mays L.) (2004-5), and soybean (2005-6). Soil samples were collected at the following depths: 0-0.05, 0.05-0.10, and 0.10-0.20m, 10 years after surface liming and 3 years after surface re-liming. Soil Zn levels were extracted by four extractants: (i) 0.005molL-1 diethylenetriaminepentaacetic acid (DTPA) + 0.1molL-1 triethanolamine (TEA) + 0.01molL-1 calcium chloride (CaCl2) solution at pH7.3 (DTPA-TEA), (ii) 0.1molL-1 hydrochloric acid (HCl) solution, (iii) Mehlich 1 solution, and (iv) Mehlich 3 solution. Zinc concentrations in leaves and grains of soybean, wheat, and corn were also determined. Soil pH (0.01molL-1 CaCl2 suspension) varied from 4.4 to 6.1, at the 0- to 0.05-m depth, from 4.2 to 5.3 at the 0.05- to 0.10-m depth, and from 4.2 to 4.8 at the 0.10- to 0.20-m depth, after liming and re-liming. Zinc concentrations evaluated by DTPA-TEA, 0.1molL-1 HCl, Mehlich 1, and Mehlich 3 solutions were not changed as a result of lime rate application. Re-liming increased Zn concentrations extracted by 0.1molL-1 HCl at 0-0.05m deep and by DTPA-TEA at 0.05-0.10m deep. Surface-applied lime promoted a decrease in Zn concentrations of the crops, mainly in grains, because of increased soil pH at the surface layers. Regardless of the liming treatments, levels of Zn were sufficient to soybean, wheat, and corn nutrition under NT.

Nitrogen and potassium fertilization affect apple fruit quality in southern Brazil

Nitrogen (N) and potassium (K) are usually found in higher concentrations than other macronutrients in apple (Malus x domestica Borkh) fruits and are most frequently associated with changes in fruit quality. The aim of this article was to evaluate the effects of N and K fertilization on some fruit quality attributes of Fuji apple. The experiment was conducted at Sao Joaquim, State of Santa Catarina, Brazil, during 2004 and 2005. A factorial design was used with N and K annual fertilizer rates (0, 50, 100, and 200 kg ha(-1) of N and K2O) replicated in three orchards. Fifteen days prior to harvest, three fruit samples were collected from each treatment and site. One sample was used for total soluble solid content (TSS), titratable acidity, pulp firmness, and fruit color parameter analyses, and the other samples were refrigerated in a conventional atmosphere for 3 and 6 months for subsequent determination of fruit quality. Nitrogen fertilization negatively affected fruit color, flesh firmness, and TSS content. These same variables were positively affected by K fertilization, except for flesh firmness.

The dynamic of shrinkage/moisture content behavior determined during drying of microsamples for different kinds of wood

This article presents the results obtained from an experimental device designed for the accurate determination of wood/water relationship on microsamples. The moisture content of the sample is measured with a highly sensitive electronic microbalance and two dimensions of the sample are collected continuously without contact using high-speed laser scan micrometers. The whole device is placed in a climatic chamber. The microsamples investigated were prepared with a diamond wire saw. The unique ability of this device to work with small samples allowed normal, opposite, and reaction wood to be characterized separately. Experiments were carried out on three wood species (beech, spruce, and poplar). In the case of beech, a deviation from the linear relation between tangential shrinkage and moisture content between 40 and 20% is particularly noticeable for the first desorption. A localized collapse of ray cells could explain this result. Compared to normal wood, an important longitudinal shrinkage and a low tangential shrinkage were observed in compression wood of spruce. Both the tension wood and opposite wood of poplar exhibit a high longitudinal shrinkage, but no significant difference between the three types of wood is noticeable in the tangential direction.

A Log-Linear Regression Model for the Beta-Weibull Distribution

We introduce the log-beta Weibull regression model based on the beta Weibull distribution (Famoye et al., 2005; Lee et al., 2007). We derive expansions for the moment generating function which do not depend on complicated functions. The new regression model represents a parametric family of models that includes as sub-models several widely known regression models that can be applied to censored survival data. We employ a frequentist analysis, a jackknife estimator, and a parametric bootstrap for the parameters of the proposed model. We derive the appropriate matrices for assessing local influences on the parameter estimates under different perturbation schemes and present some ways to assess global influences. Further, for different parameter settings, sample sizes, and censoring percentages, several simulations are performed. In addition, the empirical distribution of some modified residuals are displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be extended to a modified deviance residual in the proposed regression model applied to censored data. We define martingale and deviance residuals to evaluate the model assumptions. The extended regression model is very useful for the analysis of real data and could give more realistic fits than other special regression models.

A new species of Phaenocarpa Foerster (Hymenoptera: Braconidae: Alysiinae) from Brazil parasitizing Neosilba perezi (Diptera: Lonchaeidae)

This paper provides the description of Phaenocarpa neosilbae sp. n. (Braconidae: Alysiinae) reared from larvae of Neosilba perezi (Romero Ruppel, 1973) (Diptera: Lonchaeidae) in Brazil. Diagnostic characters are figured and the key to the Neotropical species of Phaenocarpa (Arouca Penteado-Dias, 2006) is modified to include the new species.

Influence of Urea and Ammonium Sulfate on Soil Acidity Indices in Lowland Rice Production

Urea and ammonium sulfate are principal nitrogen (N) sources for crop production. Two field experiments were conducted during three consecutive years to evaluate influence of urea and ammonium sulfate application on grain yield, soil pH, calcium (Ca) saturation, magnesium (Mg) saturation, base saturation, aluminum (Al) saturation, and acidity (H + Al) saturation in lowland rice production. Grain yield was significantly influenced by urea as well as ammonium sulfate fertilization. Soil pH linearly decreased with the application of N by ammonium sulfate and urea fertilizers. However, the magnitude of the pH decrease was greater by ammonium sulfate than by urea. The Ca and Mg saturations were decreased at the greater N rates compared to low rates of N by both the fertilizer sources. The Al and acidity saturation increased with increasing N rates by both the fertilizer sources. However, these acidity indices were increased more with the application of ammonium sulfate compared with urea. Rice grain yield had negative associations with pH, Ca saturation, Mg saturation, and base saturation and positive associations with Al and acidity saturation. This indicates that rice plant is tolerant to soil acidity.

Potassium Soil Test Calibration for Lowland Rice on an Inceptisol

Potassium (K) plays an important role in many physiological and biochemical processes in plants and its adequate use is an important issue for sustainable economic crop production. Soil test-based K fertilizer recommendations are very limited for lowland rice (Oryza sativa L.) grown on Inceptisols. The objective of this study was to calibrate K soil testing for the response of lowland rice (cv. Ipagri 109) to added K. A field experiment was conducted in the farmers` field in the municipality of Lagoa da Confusao, State of Tocantins, central Brazil. The K rates used were 0, 125, 250, 375, 500, and 625 kg K ha-1 applied as broadcast and incorporated during sowing of the first rice crop. Rice responded significantly to K fertilization during 2 years of experimentation. Maximum grain yield of about 6,000 kg ha-1 was obtained with 57 mg K kg-1 soil in the first year and with 30 mg K kg-1 in the second year. This indicated that at low levels of K in the soil, nonexchangeable K was available for plant growth. Potassium use efficiency designated as agronomic efficiency (kg grain produced/kg K applied) decreased significantly in a quadratic fashion with increasing K level in the soil. Agronomic efficiency had a significantly linear association with grain yield. Hence, improving agronomic efficiency with management practices can improve rice yield.

Yield, Potassium Uptake, and Use Efficiency in Upland Rice Genotypes

Potassium (K) is an essential nutrient for higher plants. Information on K uptake and use efficiency of upland rice under Brazilian conditions is limited. A greenhouse experiment was conducted with the objective to evaluate influence of K on yield, K uptake, and use efficiency of six upland rice genotypes grown on Brazilian Oxisol. The K rate used was zero (natural soil level) and 200 mg K kg-1 of soil. Shoot dry weight and grain yield were significantly influenced by K level and genotype treatments. However, K x genotype interactions were not significant, indicating similar responses of genotypes at two K levels for shoot dry weight and grain yield. Genotypes produced grain yield in the order of BRS Primavera BRA 01596 BRSMG Curinga BRS 032033 BRS Bonanca BRA 02582. Potassium concentration in shoot was about sixfold greater compared to grain, across two K levels and six genotypes. However, K utilization efficiency ratio (KUER) (mg shoot or grain yield / mg K uptake in shoot or root) was about 6.5 times greater in grain compared to shoot, across two K level and six genotypes. Potassium uptake in shoot and grain and KUER were significantly and positively associated with grain yield. Soil calcium (Ca), K, base saturation, acidity saturation, Ca saturation, K saturation, Ca/K ratio, and magnesium (Mg)/K ratio were significantly influenced by K application rate.

TWO NEW SPIDER MITES (ACARI: TETRANYCHIDAE) FROM BRAZIL: A MONOCERONYCHUS MCGREGOR (BRYOBIINAE) FROM FINGERGRASS AND AN OLIGONYCHUS BERLESE (TETRANYCHINAE) FROM GRAPE

Two new Tetranychidae (Prostigmata) mites are described from Brazil Monoceronychus tchecensis n. sp., a bryobiine collected from weeping fingergrass, Eustachys distichophylla (Lag.) Nees (Poaceae), in the State of Rio Grande do Sul; and Oligonychus fileno n. sp., a tetranychine collected from grape, Vitis vinifera L. (Vitaceae), in the State of Minas Gerais. Monoceronychus tchecensis n. sp. is the second species in this genus described from South America. In addition to the description of these new species, the tetranychine Eotetranychus smithi Pritchard and Baker, 1955 was recorded for the first time for South America.

Description of a new Tetranychus (Acarina, Prostigmata : Tetranychidae) pest of Musa from French Guiana

A new species of tetranychid mite, genus Tetranychus Dufour, 1832, is described and illustrated herein from neotropical area. Tetranychus musae sp. nov. (Acari, Prostigmata: Tetranychidae) differs from other species in the genus by the combination between the arrangement of leg setae on females tarsus I and the shape of the aedeagus. Tarsus I bears one tactile setae proximal to proximal duplex setae and three tactiles in line or almost in line with proximal duplex setae. The aedeagus knob consists of an acute posterior projection bent ventrally and a larger anterior rounded projection directed anterodorsally. T. musae specimens were collected in French Guiana where they appeared to be a pest of Musa sp. A key to adults of neotropical species of the genus Tetranychus feeding on banana is provided.

Antioxidant capacity of the striped sunflower (Helianthus annuus L.) seed extracts evaluated by three in vitro methods

The antioxidant capacity of the striped sunflower seed cotyledon extracts, obtained by sequential extraction with different polarities of solvents, was evaluated by three different in vitro methods: ferric reducing/antioxidant power (FRAP), 2.2-diphenyl-1-picrylhydrazyl radical (DPPH) and oxygen radical absorbance capacity (ORAC) assays. In the three methods, the aqueous extract at 30 mu g/ml showed a higher antioxidant capacity value (FRAP, 45.27 mu mol; DPPH, 50.18%; ORAC, 1.5 Trolox equivalents) than the ethanolic extract (FRAP, 32.17 mu mol; DPPH, 15.21%; ORAC, 0.50 Trolox equivalents). When compared with the synthetic antioxidant butylated hydroxyl toluene, the antioxidant capacity of the aqueous extract varied from 45% to 66%, according to the used method. The high antioxidant capacity observed for the aqueous extract of the studied sunflower seed suggests that the intake of this seed may prevent in vivo oxidative reactions responsible for the development of several diseases, such as cancer.

Enzymatic-spectrophotometric determination of paraquat in urine samples: A method based on its toxic mechanism

Paraquat is a broad-spectrum contact herbicide that has been encountered worldwide in several cases of accidental, homicidal, and suicidal poisonings. The pulmonary toxicity of this compound is related to the depletion of NADPH in the pneumocytes, which is continuously consumed by the reduction/oxidation of paraquat and reductase enzyme systems in the presence of O(2) (redox cycling). Based on this mechanism, an enzymatic-spectrophotometric method was developed for the determination of paraquat in urine samples. The velocity of NADPH consumption was monitored at 340 nm, every 10 s during 15 min. The velocity of NADPH oxidation correlated with the paraquat levels found in samples. The enzymatic-spectrophotometric method showed to be sensitive, making possible the detection of paraquat in urine samples at concentrations as low as 0.05 mg/L.

Photoprotective effect of Pothomorphe umbellata on UVB radiation-induced biomarkers involved in carcinogenesis of hairless mouse epidermis

In this study we assessed the protective effect of topical application of Pothomorphe umbellata extract on ultraviolet B (UVB)-induced skin lesion parameters in hairless mouse epidermis. A single dose of UVB irradiation (0.23 kJ/m(2)) resulted in a significant decrease in thymine dimer-positive cells and apoptotic sunburn cells, with an increase in p53 and proliferating cell nuclear antigen-positive cells in the epidermis. After 5 weeks (total dose 13.17 kJ/m(2)) and 15 weeks (total dose 55.51 kJ/m(2)) of irradiation, P. umbellata treatment inhibited the hyperplasic response and induced an increase in p53-positive cells. These findings suggest that P. umbellata extract affords protection against UVB-induced skin lesions.

Cruzain inhibition by hydroxymethylnitrofurazone and nitrofurazone: investigation of a new target in Trypanosoma cruzi

Nitrofurazone (NF) and its derivative, hydroxymethylnitrofurazone (NFOH), have presented antichagasic activity. NFOH has higher activity and lower mutagenicity. The aim of this work was to assess whether NF and its derivative NFOH would also be inhibitors of cruzain, besides their trypanothione reductase inhibitory activity. In vitro cruzain inhibition tests were performed for both compounds, and the 50% inhibitory concentration (IC(50)) for NF and NFOH presented values of 22.83 +/- 1.2 mu M and 10.55 +/- 0.81 mu M, respectively. AM1 semi-empirical molecular modeling studies were performed to understand the activity of the compounds, corroborating the observed cruzain inhibitory activity.