South American leaf blight intensity evaluated in six clones of young and adult rubber trees in the Vale do Ribeira region, Sao Paulo state, Brazil

Rubber tree clones present different intensity of symptoms, depending on their age. This is mostly clearly seen in the presence or absence of old leaves with ascopores, corresponding to flows of new and susceptible leaves. The objective of this work was to evaluate the intensity of symptoms of south American leaf blight (SALB) in six rubber tree clones, one and eight years old, in the Vale do Ribeira region, Sao Paulo state. The results Showed that clones FX 3864, RRIM 600, IAN 873 and IAN 717 Suffered more attacks when young, and RRIM 600, IAN 717 and FX 3864 when adult. The clone IAN 873 showed the smallest amounts of disease in the adult phase, due to uniform change in the leaves and a compact flow of new leaves, which happened during a season that was unfavorable to pathogen infection, presenting the phenomenon of avoidance or evasion in time.

Ammonia volatilization in soil treated with tannery sludge

The utilization of tannery sludge in agricultural areas can be an alternative for its disposal and recycling. Despite this procedure may cause the loss of nitrogen by ammonia volatilization, there is no information about this process in tropical soils. For two years a field experiment was carried out in Rolandia (Parana State, Brazil), to evaluate the amount of NH(3) volatilization due to tannery sludge application on agricultural soil. The doses of total N applied varied from zero to 1200 kg ha(-1), maintained at the surface for 89 days, as usual in this region. The alkalinity of the tannery sludge used was equivalent to between 262 and 361 g CaCO(3) per kg. Michaelis-Menten equation was adequate to estimate NH(3)-N volatilization kinetics. The relation between total nitrogen applied as tannery sludge and the potentially volatilized NH(3)-N, calculated by the chemical-kinetics equation resulted in an average determination coefficient of 0.87 (P > 0.01). In this period, the amount of volatilized NH(3) was more intense during the first 30 days; the time to reach half of the maximum NH(3) volatilization (K(m)) was 13 an 9 days for the first and second experiments, respectively. The total loss as ammonia in the whole period corresponded in average to 17.5% of the total N applied and to 35% of the NH(4)(+)-N present in the sludge. If tannery sludge is to be surface applied to supply N for crops, the amounts lost as NH(3) must be taken into consideration. (C) 2010 Elsevier Ltd. All rights reserved.

Sodicity and salinity in a Brazilian Oxisol cultivated with sugarcane irrigated with wastewater

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.

Nickel adsorption in two Oxisols and an Alfisol as affected by pH, nature of the electrolyte, and ionic strength of soil solution

Background, aim, and scope The retention of potentially toxic metals in highly weathered soils can follow different pathways that variably affect their mobility and availability in the soil-water-plant system. This study aimed to evaluate the effects of pH, nature of electrolyte, and ionic strength of the solution on nickel (Ni) adsorption by two acric Oxisols and a less weathered Alfisol. Materials and methods The effect of pH on Ni adsorption was evaluated in surface and subsurface samples from a clayey textured Anionic `Rhodic` Acrudox ( RA), a sandy-clayey textured Anionic `Xantic` Acrudox (XA), and a heavy clayey textured Rhodic Kandiudalf (RK). All soil samples were equilibrated with the same concentration of Ni solution (5.0 mg L(-1)) and two electrolyte solutions (CaCl(2) or NaCl) with different ionic strengths (IS) (1.0, 0.1 and 0.01 mol L(-1)). The pH of each sample set varied from 3 to 10 in order to obtain sorption envelopes. Results and discussion Ni adsorption increased as the pH increased, reaching its maximum of nearly pH 6. The adsorption was highest in Alfisol, followed by RA and XA. Competition between Ni(2+) and Ca(2+) was higher than that between Ni(2+) and Na(+) in all soil samples, as shown by the higher percentage of Ni adsorption at pH 5. At pH values below the intersection point of the three ionic strength curves (zero point of salt effect), Ni adsorption was generally higher in the more concentrated solution (highest IS), probably due to the neutralization of positive charges of soil colloids by Cl(-) ions and consequent adsorption of Ni(2+). Above this point, Ni adsorption was higher in the more diluted solution (lowest ionic strength), due to the higher negative potential at the colloid surfaces and the lower ionic competition for exchange sites in soil colloids. Conclusions The effect of ionic strength was lower in the Oxisols than in the Alfisol. The main mechanism that controlled Ni adsorption in the soils was the ionic exchange, since the adsorption of ionic species varied according to the variation of pH values. The ionic competition revealed the importance of electrolyte composition and ionic strength on Ni adsorption in soils from the humid tropics. Recommendations and perspectives The presence of NaCl or CaCl(2) in different ionic strengths affects the availability of heavy metals in contaminated soils. Therefore, the study of heavy metal dynamics in highly weathered soils must consider this behavior, especially in soils with large amounts of acric components.

Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol-Podzol sequence of the upper Amazon Basin

Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.

Plant availability of phosphorus in four superphosphate fertilizers varying in water-insoluble phosphate compounds

There is concern that the use of lower quality phosphate rock can result in elevated amounts of Fe-Al-P water-insoluble compounds in fertilizers and, consequently, low agronomic effectiveness. Therefore, studies were conducted to evaluate the effect of some of these compounds on plant growth. Four commercial superphosphates varying in chemical composition (two single and two triple superphosphates) were selected for the study. Fertilizer impurities were collected as water-insoluble residues by washing each P source with deionized water. A modal analysis, based primarily on elemental chemical analysis and x-ray diffractometry, was used to estimate the chemical composition of each P source. Water-soluble monocalcium phosphate (MCP) and the water-leached fertilizer residues were prepared to give a range of fertilizers in terms of water-soluble phosphorus (WSP) (0-100% of the available P as MCP). The water-leached fractions, MCP, and the mixtures of MCP with water-leached fractions were applied to supply 40 mg available P kg(1) to a thermic Rhodic Kanhapludult with pH values of 5.2 +/- 0.05 (unlimed) and 6.4 +/- 0.08 (limed). Wheat (Triticum aestivum L.) grown in a greenhouse for 101 d served as the test crop. The requirement for WSP was source and pH dependent. At a soil pH of 5.2, the fertilizers required 73 to 95% WSP to reach the maximum dry-matter yield, while they required 60 to 86% WSP at pH 6.4. To reach 90% of the maximum yield, all superphosphate fertilizers required <50% WSP. These results show that it is not always necessary to have high water solubility as required by legislation in many countries.

Greenhouse gases emission from soil contaminated with automobile industry residue in Brazil

Solid waste of the automobile industry containing large amounts of heavy metals might affect the emission of greenhouse gases (GHG) when applied to the soil. Accumulation of inorganic chemical elements in the environment generally occurs due to human activity (industry, agriculture, mining and waste landfills). Residues from human activities may release heavy metals to the soil solution, causing toxicity to plants and other soil organisms. Heavy metals may also be adsorbed to clay minerals and/or complexed by the soil organic matter, becoming a potential source of pollutants. Not much is known about the behavior of solid wastes in tropical soil as regarded as source of greenhouse gases (GHG). The emission of GHG (CO(2), CH(4) and N(2)O) was evaluated in incubated soil samples collected in an area contaminated with a solid residue from an automobile industry. Samples were randomly collected at 0 to 0.2 m (a mix of soil and residue), 0.2 to 0.4 m (only residue) and 0.4 to 0.6 m (only soil). A contiguous uncontaminated area, cultivated with sugarcane, was also sampled following the same protocol. Canonical Discriminant Analysis and Principal Component Analysis were applied to the data to evaluate the GHG emission rates. Emission rates of GHG were greater in the samples from the contaminated than the sugarcane area, particularly high during the first days of incubation. CO(2) emissions were greater in samples collected at the upper layer for both areas, while CH(4) and N(2)O emissions were similar in all samples. The emission rates of CH(4) were the most efficient variables to differentiate contaminated and uncontaminated areas.

Micronutrient dynamics in the forest biomass in succession stages of a seasonal deciduous forest, RS, Brazil

There is a great need of research to assess the behavior of micronutrients in natural forests of southern Brazil. Do to this need, the objective of this work was to study the levels and amounts of micronutrients in forest above ground biomass of the forest, in a comparative way, in two secondary succession stages (SSS) in a Seasonal Deciduous Forest in Rio Grande do Sul, Brazil. The SSS had enjoyed 35 and 55 years of regeneration since the end of agricultural use, respectively for initial secondary forest (ISF) and late secondary forest (LSF). The above-ground biomass was collected and separated into vegetative strata and these in fractions, thereafter chemically analyzed for the levels of B, Fe, Zn, Mn and Cu. Leaf fractions of arboreal, shrubs and herbaceous strata showed the highest levels for most nutrients. Only the levels of iron and manganese were higher in the bark fraction, for both sucession stages. In the LSF, the herbaceous stratum also showed high levels of Fe. The average levels of micronutrients showed differences between the two sucession stages only in relation to Fe and Mn, with higher levels in LSF biomass. The amount of nutrients stored was always higher in LSF, because of the largest biomass and the higher levels of Fe and Mn in the biomass of this SSS. The quantitative order of nutrient storage in biomass was Fe> Mn> Zn> B> Cu.

Relationship between occurrence of Panama disease in banana trees of cv. Nanicao and nutrients in soil and leaves

Relationship between occurrence of Panama disease in banana trees of cv. Nanicao and nutrients in soil and leaves The objective of the present work was to verify if the incited symptoms in banana trees cv. Nanicao, belonging to the subgroup Cavendish, in Vale do Ribeira, are related to levels of nutrients in soil and leaves. Sixteen areas in Vale do Ribeira were selected, one half with symptomatic plants and the other with healthy plants. In those areas the third leaf of five plants and the soil near those plants were collected, at depths from 0 to 20 cm and from 20 to 40 cm. At both depths of the sampled soil, levels of Ca, Mg, PO(4)(-3), S and cationic exchange capacity (CEC) were significantly different among the areas, and the low values of these elements were present in the areas containing symptomatic plants. At both depths, Mg, Al and H in relation to CEC were significantly different among the areas, and the low values of Mg and high of Al and H were present in the areas with symptomatic plants. The N, K and S in the leaves were significantly different among the areas. These elements showed low values in the areas containing symptomatic plants. Despite the fact that some amounts of macronutrients of the soil and of the leaves are present only in the areas containing plants of Nanicao with symptoms similar to fusariosis, proof of a possible occurrence of race of the pathogen should be looked for in Vale do Ribeira.

Nutritional Aspects of Second Generation Soy Foods

Samples of 15 second generation soy-based products (n = 3), commercially available, were analyzed for their protein and isoflavone contents and in vitro antioxidant activity, by means of the Folin-Ciocalteu reducing ability, DPPH radical scavenging capacity, and oxygen radical absorbance capacity. Isoflavone identification and quantification were performed by high-performance liquid chromatography. Products containing soy and/or soy-based ingredients represent important sources of protein in addition to the low fat amounts. However, a large variation in isoflavone content and in vitro antioxidant capacity was observed. The isoflavone content varied from 2.4 to 18.1 mg/100 g (FW), and soy kibe and soy sausage presented the highest amounts. Chocolate had the highest antioxidant capacity, but this fact was probably associated with the addition of cocoa liquor, a well-known source of polyphenolics. This study showed that the soy-based foods do not present a significant content of isoflavones when compared with the grain, and their in vitro antioxidant capacity is not related with these compounds but rather to the presence of other phenolics and synthetic antioxidants, such as sodium erythorbate. However, they may represent alternative sources and provide soy protein, isoflavones, and vegetable fat for those who are not ready to eat traditional soy foods.

Increased expression of fructan 1-exohydrolase in rhizophores of Vernonia herbacea during sprouting and exposure to low temperature

Rhizophores of Vernonia herbacea, an Asteraceae found in the Brazilian Cerrado, store high amounts of fructans that vary in composition over the phenological cycle. Fructan 1-exohydrolase (1-FEH) activity is detectable during the sprouting phase, mainly in the proximal regions of rhizophores, of plants induced to sprout by defoliation and/or cold storage. We found an increase in 1-FEH gene expression during natural and induced sprouting and further enhancement through low-temperature treatment. Furthermore, a comparative analysis of 1-FEH gene expression in different regions of the rhizophores during the transition from dormancy to sprouting is presented. Transcripts were detected mainly in the proximal region, coinciding with high 1-FEH activity and a high concentration of free fructose. Low temperature promoted the accumulation of fructans of a low degree of polymerization (DP) and enhanced 1-FEH activity and gene expression. It is hypothesized that a set of 1-FEH proteins acts in two different ways during fructan mobilization: (1) by hydrolyzing fructo-oligosaccharides and -polysaccharides in sprouting plants (naturally or induced) for carbon supply and (2) by hydrolyzing preferably fructo-polysaccharides under low temperature to maintain the oligosaccharide pool for plant cold acclimation. (C) 2010 Elsevier GmbH. All rights reserved.

Phenolic composition and antioxidant activity of culms and sugarcane (Saccharum officinarum L.) products

The present work reports amounts of flavonoids and phenylpropanoids of culms of three sugarcane varieties and of raw juice, syrup, molasse and VHP sugar. The antioxidant activity of those materials was evaluated by the DPPH and beta-carotene/linoleic acid methods. The predominant phenolics in culms were phenylpropanoids (caffeic, chlorogenic and coumaric acids), while flavones (apigenin, tricin and luteolin derivatives) appeared in lower amounts. Differences were noted either among phenolic profiles of sugarcane culms or between culms and sugarcane products. The antioxidant activities of solutions from most samples were similar or higher than a 80 mu M Trolox solution. (C) 2010 Elsevier Ltd All rights reserved.

Effect of Brazil nut supplementation on the blood levels of selenium and glutathione peroxidase in hemodialysis patients

Objective: In patients who have undergone hemodialysis, large amounts of reactive oxygen species (ROS) are produced and, at higher concentrations, ROS are thought to be involved in the pathogenesis of cardiovascular disease. It has been proposed that selenium (Se) may exert an anti-atherogenic influence by reducing oxidative stress. The richest known food source of selenium is the Brazil nut (Bertholletia excelsa, family Lecythidaceae), found in the Amazon region. We evaluated the effect of Brazil nut supplementation on blood levels of Se and glutathione peroxidase (GSH-Px) activity in patients on hemodialysis. Methods: A total of 81 patients on hemodialysis (52.0 +/- 15.2 y old, average time on dialysis 82.3 +/- 91.4 mo, body mass index 24.9 +/- 4.4 kg/m(2)) from the RenalCor and RenalVida Clinics in Rio de Janeiro, Brazil, were studied. All patients received one nut (around 5 g, averaging 58.1 mu g Se/g) a day for 3 mo. The Se concentrations in the nuts and in plasma and erythrocytes were determined by atomic absorption spectrophotometry with hydride generation (Hitachi, Z-500). GSH-Px levels were measured using Randox commercial kits. Results: Plasma Se (18.8 +/- 17.4 mu g/L) and erythrocyte (72.4 +/- 37.9 mg/L) levels were below the normal, range before nut supplementation. After supplementation, the plasma level increased to 104.0 +/- 65.0 mu g/L and erythrocytes to 244.1 +/- 119.5 mg/L (P<0.0001). The activity of GSH-Px also increased after supplementation, from 46.6 +/- 14.9 to 55.9 +/- 23.6 U/g of hemoglobin (P<0.0001). Before supplementation, 11% of patients had GSH-Px activity below the normal range (27.5-73.6 U/g of hemoglobin). After supplementation, all patients showed GSH-Px activity within the normal range. Conclusion: The data revealed that the investigated patients presented Se deficiency and that the consumption of only one Brazil nut a day (5 g) during 3 mo was effective to increase the Se concentration and GSH-Px activity in these patients, thus improving their antioxidant status. (C) 2010 Elsevier Inc. All rights reserved.

Rheological and functional properties of flours from banana pulp and peel

Unripe banana flour can be an alternative to minimize post-harvest loss and to increase the aggregate value of banana fruit. Flour from unripe banana is rich in phytosterols and resistant starch, being proposed as health food. Flours from unripe banana peel and pulp were evaluated on their composition, phytosterols content, thermal and rheological properties, and pasting profiles. High amounts of beta-sitosterol, campesterol, and stigmasterol were found in flour from banana peel. These samples showed lower viscosity values of pasting profiles, lower energy enthalpy on gelatinization, and higher temperature of gelatinization than those ones from pulp. Anti-oxidant treatment of fruits with citric acid does not change pasting profiles of flours from pulp, but resulted in slight increase in viscosity, suggesting that structure of starch could be modified by acidification.

Comparative study of phenolic compounds in different Brazilian rice (Oryza sativa L.) genotypes

This study was conducted to evaluate the natural variability of total, extractable and non-extractable phenolics in pigmented and non-pigmented rice genotypes (Oryza sativa L.) and to estimate whether the contents and distribution of these compounds are typical for genotypes from indica and japonica subspecies. Twenty-one samples of commercial as well as new genotypes of brown rice, including seven pigmented genotypes were obtained from two Agronomic Institutes in South Brazil. Free and conjugated phenolics were extracted with ethanol, while bound phenolics were released by alkaline hydrolysis. Total phenolics were estimated in both fractions by the Folin-Ciocalteau method. Genotypes from Japonica and indica non-pigmented subspecies were not statistically distinguishable from each other, but differences in phenolic contents were associated with pericarp color. Despite individual differences, total phenolics were four times higher in pigmented than in non-pigmented genotypes (4246 and 1073 mg ferulic acid equiv. kg(-1), respectively). These high amounts were mostly due to the presence of extractable (free and conjugated) phenolics, which comprised up to 81% of total phenolics for pigmented genotypes. Non-extractable (bound) phenolics comprised 40% of total phenolics of non-pigmented rice genotypes while pigmented genotypes presented greater absolute amounts, but their contribution on total phenolics was small. (C) 2008 Elsevier Inc. All rights reserved.