Resumen El nitrógeno (N) y el azufre (S) son nutrientes, que además de influir en el crecimiento y producción de las plantas, interfieren en procesos relacionados con la calidad del fruto poscosecha. En el presente estudio se evalúo interacción N x S en la calidad poscosecha de tomate( Solanum lycopersicum L.). El experimento fue conducido en invernadero utilizando vasos de 5 dm3 de capacidad que contenian una capa de 0-20 cm de un Latosol Rojo distroférrico. Se utilizó un diseño factorial 5 x 3, con combinaciones de cinco dosis de N (0, 100, 200, 300 y 400 mg dm-3) y de tres de S (0, 60 y 120 mg dm-3) distribuidas en un diseño completamente aleatorio, con cuatro repeticiones. Después de la cosecha se evaluaron los atributos de la calidad del fruto: firmeza, pH, sólidos solubles (SS), acidez titulable (AT), relación sólidos solubles y acidez titulable (SS/AT), vitamina C, licopeno y betacaroteno. Se observó un aumento de la firmeza, así como del contenido de solidos solubles, acidez titulable y la relación SS/AT de los frutos como resultado la interacción N x S. No obstante esta interacción favoreció la reducción de los contenidos de vitamina C, licopeno y betacaroteno, y las características de calidad de fruto del tomate en relación con los valores recomendados. Sólo las dosis crecientes de N favorecieron un mayor pH en los frutos de tomate.

Abstract Nitrogen (N) and sulfur (S) are nutrients that, in addition to influencing plant growth and production, interfere with processes related to postharvest fruit quality. In the present study, N x S interaction was evaluated in the postharvest quality of tomato (Solanum lycopersicum L.). The experiment was conducted in a greenhouse using 5 dm3 capacity vessels containing a 0-20 cm layer of a dystropherric Red Latosol. A 5 x 3 factorial design was used, with combinations of five doses of N (0, 100, 200, 300 and 400 mg dm-3) and three doses of S (0, 60 and 120 mg dm-3) distributed in a completely randomized design, with four repetitions. After harvest, the attributes of fruit quality were evaluated: firmness, pH, soluble solids (SS), titratable acidity (AT), soluble solids ratio and titratable acidity (SS / AT), vitamin C, lycopene and beta-carotene. An increase in firmness was observed, as well as the content of soluble solids, titratable acidity and the SS / AT ratio of the fruits as a result of the interaction N x S. However, this interaction favoured the reduction of the contents of vitamin C, lycopene and beta-carotene, and the quality characteristics of tomato fruit in relation to the recommended values. Only the increasing doses of N favoured a higher pH in the tomato fruits.

Large areas of land are nowadays contaminated by heavy metals and, it is therefore, important to monitor their levels in soils. Vegetables act as transfer mechanisms of such contaminants from soils to higher levels in the food chain. In this study, we aimed to evaluate the effectiveness of chemical extractants by the L-value method for Cd phytoavailability using the 109Cd radionuclide. In a greenhouse experiment, rocket plants (Eruca sativa L.) were cultivated in pots with samples from Typic Hapludox and Typic Quartzipsamment soils. Cadmium concentrations ranging from 0 to 16 mg kg-1 were added to a 200 mL solution containing 148 kBq 109Cd. The available Cd in the soil was extracted by DTPA, Mehlich-1, Mehlich-3, and a mixture of organic acids (acetic, citric, lactic, and oxalic acids). Cd concentrations were determined by atomic absorption spectrophotometry, and 109Cd radionuclide activity was measured by low-level β-counting. The dry matter yield was not influenced by Cd rates, but the Cd content and accumulation in shoots had a positive linear correlation. Generally, Cd was extracted in higher quantities by Mehlich-1 followed by DTPA, Mehlich-3, and organic acids. A linear correlation was found between the chemical extractants and Cd accumulation in shoots for both soils. According to the L Ratio, the extractants based on strong acids and chelating agents presented low efficiency regarding Cd phytoavailability. The organic acids, which presented values close to the L-value, may provide a promising method for evaluating environmental contaminants.

Os metais pesados podem-se acumular no solo, causando fitotoxicidade em plantas, apresentando alguns sintomas específicos. Por esta razão, este estudo avaliou os sintomas específicos, em plantas de arroz e de soja, causados por excesso de metais pesados no solo. As plantas de arroz e de soja foram cultivadas em vasos, contendo solos com diferentes quantidades de metais pesados. O delineamento experimental foi inteiramente casualizado, com quatro repetições, utilizando-se duas culturas e sete amostras de solos com diferentes níveis de contaminação. As plantas de arroz e de soja exibiram diferentes respostas às elevadas concentrações desses metais no solo. Por exemplo, altas concentrações de Zn disponível no solo causaram fitotoxicidade no arroz e na soja, principalmente cloroses e inibição do crescimento das plantas. As plantas de arroz acumularam maiores teores de Cu, Mn, Pb e Zn e foram mais sensíveis às concentrações elevadas desses elementos no solo, absorvendo-os mais facilmente do que as plantas de soja. Além disso, altas concentrações de Zn no solo reduziram a concentração de Fe na parte aérea das plantas de soja e de arroz para níveis considerados deficientes.

Heavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentration in the shoots of soybean and rice plants to levels considered deficient.

Ingestion of vegetables containing heavy metals is one of the main ways in which these elements enter the human body. Once entered, heavy metals are deposited in bone and fat tissues, overlapping noble minerals. Slowly released into the body, heavy metals can cause an array of diseases. This study aimed to investigate the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequently consumed foodstuff in the São Paulo State, Brazil and to compare the heavy metal contents with the permissible limits established by the Brazilian legislation. A value of intake of heavy metals in human diets was also calculated to estimate the risk to human health. Vegetable samples were collected at the São Paulo General Warehousing and Centers Company, and the heavy metal content was determined by atomic absorption spectrophotometry. All sampled vegetables presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Pb and Cr exceeded the limits in 44 % of the analyzed samples. The Brazilian legislation does not establish a permissible limit for Co contents. Regarding the consumption habit of the population in the São Paulo State, the daily ingestion of heavy metals was below the oral dose of reference, therefore, consumption of these vegetables can be considered safe and without risk to human health.

The objective of the study was to evaluate the effect of phosphorus on the Cd availability to plants of a contaminated soil using 109Cd isotope and chemical extractants. The experiment was set in a randomized block design and the soil was labeled with 222 KBq of 109Cd per pot and received 5 rates of P as triple superphosphate, growing lettuce plants as test crop. The use of phosphorus reduced pH of soil which altered the Cd availability in DTPA and Mehlich extractants. The lettuce Cd content decreased but its accumulation and L value increased in all treatments compared to the control, demonstrating the inefficiency of phosphorus in reducing the Cd availability.

Os elementos traços são potencialmente tóxicos para o meio ambiente. Estas toxicidades dependem de suas associações químicas. Por isso a determinação da forma química destes elementos no solo é importante para quantificá-lo. O objetivo do presente trabalho foi avaliar a possibilidade de se utilizar teores de Cu e Zn nas diferentes frações do solo para prognosticar suas disponibilidades. Para isso, compararam-se as mesmas com soluções extratoras clássicas, como DTPA, Mehlich-1 e HCl, e com teores absorvidos por plantas de arroz e soja em materiais de solos contaminados. Foram estudadas sete amostras de solos com diferentes graus de contaminação empregando delineamento experimental inteiramente casualizado, com quatro repetições. Utilizando a técnica de ICP-OES, foram avaliados teores de Cu e Zn em folha diagnóstico e folha em final de ciclo (LCE) e no solo: teores disponíveis utilizando as soluções extratoras DTPA, Mehlich-1 e HCl, teores nas frações de solo solúvel+trocável, ligados à matéria orgânica e ligados a óxidos e o teor total. Para a soja e arroz, os teores de Cu e Zn extraídos do fracionamento correlacionaram significativamente com os teores obtidos na LCE. Para a soja, os teores de Zn extraídos com DTPA apresentaram alta correlação com os teores totais, enquanto que os teores de Cu extraídos pelos três extratores, DTPA, Mehlich-1 e HCl, correlacionaram com o teor total, provavelmente devido aos altos teores de Cu e Zn neste solo. Para o arroz, os teores de Cu e Zn extraídos pelas três soluções correlacionaram com teores em todas as frações e com o teor total.

Trace elements are potentially toxic to the environment. Their toxicity in soils relies on their type of chemical associations. Hence it is important to determine the chemical form they occur in the soils in order to assess their quantities. The objective the present work was to evaluate the possibility of using the concentrations of Cu and Zn in different soil fractions and the total concentration as predictors of their quantification by comparing the classical extractants DTPA, Mehlich-1 and HCl. Comparisons were made also with the concentrations of absorbed by rice and soybean in contaminated soil. Seven soil samples with a different degree of contamination were studied using a randomized experimental design, with four replicates. By using an ICP-OES we analyzed the concentrations of Cu and Zn in the diagnostic leafs, at the end of the cycle (LCE) and several of its content in the soil: available extracted with the DTPA, Mehlich-1 and HCl extractants, soluble+exchangeable contents, bound to organic matter, to oxides and the total content. For both, soybean and rice, the concentrations of Cu and Zn extracted from the sequential extraction was found to be correlated with the concentration in LCE. For soybean, Zn concentration extracted with DTPA was correlated with the total concentration, while Cu concentration extracted with three extractors, DTPA, Mehlich-1 and HCl, correlated with the total concentration, probably due to the high concentration of Cu and Zn in this soil. For rice, both Cu and Zn concentration as extracted by the three extracting solutions correlated with the concentration of all the fractions and with the total concentration.

The Cd phytoavailability in sewage sludge-amended soils of different pHs using the 109Cd L-value isotopic method and Cd extracted by DTPA has been determined. Maize plants (Zea mais L.) were grown under greenhouse conditions in a xanthic ferralsol at different pHs amended with five sewage sludge (SS) rates, and labeled with 74 kBq kg-1 of 109Cd. The SS rates altered the properties of the soil chemicals and these influenced the isotopic parameter (L-value) and percent of Cd uptake by plants from soil (%Cdpdfs) and SS (%CdpdfSS). L-values and Cd extracted by DTPA correlate significantly with SS rates and Cd uptake by plants and are efficient for predicting the Cd phytoavailability in the sewage sludge-amended soil.

The alteration of soil chemicals and its influence on availability (DTPA extractant method) and phytoavailability (63Ni L-value, isotopic method) of Ni was studied in sewage sludge-amended soil at different pHs. The soil pHs were 4.3, 5.3 and 5.9 and the rates of sewage sludge (SS) 0, 15, 30, 45 and 60 Mg ha-1. The chemical and physicochemical soil characteristics were altered by the SS rate and increased the Ni availability and phytoavailability. The isotopic method (63Ni L-value) was more efficient in predicting the Ni phytoavailability that the Ni-DTPA extractant in soil pHs 5.3 and 5.9.

O objetivo deste trabalho foi avaliar a absorção e a capacidade de translocação de metais pesados do solo para os grãos de soja e arroz. O experimento foi realizado em casa de vegetação, em Latossolo Vermelho distroférrico, proveniente de Município de Paulínia, SP. As amostras de solo foram coletadas em sete pontos e organizadas em função da distância de uma fábrica emissora de poluente. O delineamento utilizado foi o inteiramente casualizado, com quatro repetições. Raízes, parte aérea e grãos foram submetidos à digestão por via úmida. A concentração dos metais pesados foi determinada por ICP-OES. Os teores de cádmio e cobre no grão estiveram em níveis adequados para ambas as culturas, enquanto os teores de manganês e zinco apresentaram-se em excesso, tendo acompanhado os níveis de contaminação do solo, com possibilidade de atingir níveis mais altos da cadeia trófica. As raízes limitaram a translocação de cádmio, cobre, ferro e chumbo para a parte aérea de ambas as culturas. Mesmo com a translocação limitada pelas raízes, o chumbo apresentou-se em altos teores nos grãos de soja, e pode, também, como o manganês e o zinco, atingir a cadeia alimentar.

The aim of this work was to evaluate the absorption and capacity of translocation of heavy metals from the soil to rice and soybean grains. Experiment was carried out in a greenhouse using a dystrophic Typic Hapludox soil from the district of Paulínia, SP. Soil samples were collected in seven different points and were organized according to the distance from a factory, source of pollution. The experimental design used was the completely randomized, with four replications. The roots, aerial leaves and grains were submitted to humid digestion. The concentrations of heavy metals were determined by ICP-OES. Cadmium and copper concentrations in the grains were at normal levels for both cultures, however manganese and zinc concentrations were in excess, according to the levels of soil contamination, possibly being able to reach top trophic levels. The roots limited the translocation of cadmium, copper, iron and lead to the aerial parts of both cultures. Although the translocation of lead was also limited by the roots, it was present in high concentrations in soy grains and, well as manganese and zinc, it can reach the food chain.

Como geralmente os solos usados para plantações de eucalipto no Brasil são de baixa fertilidade, a adubação fosfórica é indispensável, incrementando o custo da plantação. Espécies mais eficientes no uso de fósforo (P) de fontes pouco solúveis poderiam ser uma opção interessante. Porém, pouco se conhece ainda sobre o comportamento de eucalipto em relação à capacidade de usar fósforo de fontes com diferente solubilidade em água. O uso de P por eucalipto (E. urophylla, E. grandis, and E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis), foi estudado em experimento de casa de vegetação usando solo da Região de Cerrado, Latossolo Vermelho Amarelo hypodistrófico, e o método isotópico com 32P. As fontes de P usadas foram superfosfato triplo (SFT), rocha fosfórica (RF) e a mistura de superfosfato triplo com rocha fosfórica (SFT+RF). A eficácia das fontes de P em termos do aumento do rendimento de matéria seca seguiu a ordem SFT = (SFT + RF) > RF e de P absorvido a ordem (SFT + RF) > SFT > RF por ambas as espécies e o híbrido de eucalipto. O incremento na absorção de P de RF, influenciada pela mistura com SFT foi de 217,3% em E. urophylla, 235,7% em E. grandis e 28,7% em E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis, indicando o efeito benéfico do SFT sobre a efetividade da RF. O híbrido E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis foi o genótipo mais eficiente no uso de P do solo e E. grandis o mais exigente em P do fertilizante.

Eucalyptus plantation in Brazil is generally set on low fertility soils, therefore phosphorus (P) fertilization is mandatory and increases the cost of plantation operation. Using species that more efficiently uptake phosphorus from less soluble sources is an interesting option. However, little is known about eucalyptus regarding its ability of using less soluble forms of phosphorus. The use of P by eucalyptus (E. urophylla, E. grandis, and E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis) was studied in greenhouse using a loamy-textured, hipodystrophic Typic Haplustox from the Cerrado region, and 32P isotopic method. The P sources tested were triple superphosphate (TSP), phosphate rock (PR) and the triple superphosphate mixed with PR (TSP+PR). The effectiveness of P sources in terms of increasing dry matter yield was TSP = (TSP + PR) > PR, and the P uptake followed the order (TSP + PR) > TSP > PR for both species plus the hybrid. The increase in P uptake from PR due to TSP influence was 217.3% for E. urophylla, 235.7% for E. grandis, and 28.7% for E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis, indicating an enhancement effect of TSP on the effectiveness of PR. The hybrid E. urophylla <FONT FACE=Symbol>´</FONT> E. grandis was the most efficient genotype on P soil use and E. grandis most exigent in P fertilizer.