Cachoeirinha, Brazil
Cachoeirinha, Brazil

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Caldas S.S.,Grande Rio University | Bolzan C.M.,Grande Rio University | Cerqueira M.B.,Grande Rio University | Tomasini D.,Grande Rio University | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2011

A new method for the determination of clomazone, fipronil, tebuconazole, propiconazole, and azoxystrobin in samples of rice paddy soil is presented. The extraction of the pesticides from soil samples was performed by using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Some extraction conditions such as salt addition, sample acidification, use of buffer, and cleanup step were evaluated. The optimized method dealt with a single extraction of the compounds under study with acidified acetonitrile, followed by the addition of MgSO4 and NaCl prior to the final determination by liquid chromatography-atmospheric chemical pressure ionization-tandem mass spectrometry. Validation studies were carried out in soil samples. Recoveries of the spiked samples ranged between 70.3 and 120% with relative standard deviation lower than 18.2%. The limits of quantification were between 10 and 50 μg kg-1. The method was applied to the analysis of real samples of soils where rice is cultivated. © 2011 American Chemical Society.

Dors G.C.,Grande Rio University | Primel E.G.,Grande Rio University | Fagundes C.A.A.,Instituto Rio Grandense do Arroz | Mariot C.H.P.,Instituto Rio Grandense do Arroz | Badiale-Furlong E.,Grande Rio University
Journal of the Brazilian Chemical Society | Year: 2011

Pesticides are used to prevent pests from attacking grains in order to preserve the crops. This paper aims at evaluating the distribution of the pesticides bispyribac-sodium, carbofuran, clomazone and tebuconazole in different fractions of milled rice (white rice, rice bran, husked rice, parboiled rice, parboiled rice bran, and husked parboiled rice) which is planted on experimental felds under controlled conditions. The QuEChERS method was adapted to the extraction of pesticides and validated by using HPLC-DAD for quantifcation and LC-MS for confrmation. The analytical method of extracting pesticides, as well as the chromatographic conditions for identifcation and quantifcation, were suitable, according to certain effciency indicators: 0.07 mg kg -1 LOD and 0.2 mg kg -1 LOQ for the mixture of pesticides and rice and rice bran recoveries of 119 and 116%, 84 and 119%, 113 and 96%, 103 and 97% for carbofuran, bispyribac-sodium, clomazone and tebuconazole, respectively. The method under development was applied to rice fractions: bran had the highest residue concentration of the studied pesticides, when compared to milled rice, showing 8.0, 2.3, 2.2 and 1.6 times more contamination, in average, with tebuconazole, clomazone, carbofuran and bispyribac-sodium, respectively. Only clomazone and tebuconazole were in the acceptable limits established by Codex Alimentarius (0.1 mg kg -1) for milled rice. © 2011 Sociedade Brasileira de Química.

Escarrone A.L.V.,Grande Rio University | Caldas S.S.,Grande Rio University | Furlong E.B.,Grande Rio University | Meneghetti V.L.,Instituto Rio Grandense Do Arroz | And 3 more authors.
Food Chemistry | Year: 2014

This study aims at developing a method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in rice grain samples by combining the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and determination by gas chromatography-mass spectrometry (GC-EI-MS). Quantification limits ranging from 1 to 5 μg kg-1 were obtained. Recoveries ranged from 70% to 106% for most of the 16 PAHs under analysis. The optimised methodology was applied to assess safety concerning the content of PAHs in white and parboiled rice samples, dried by gas and wood burning. Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the samples, naphthalene and phenanthrene were detected in all of them. Since cereals have been shown to be an important source of PAHs in the diet, methods that perform the evaluation of the quality of this food group become relevant. © 2013 Elsevier Ltd. All rights reserved.

Heidtmann-Bemvenuti R.,Grande Rio University | Santos Hackbart H.C.D.,Grande Rio University | De Souza M.M.,Grande Rio University | Badiale-Furlong E.,Grande Rio University | And 2 more authors.
Quimica Nova | Year: 2012

The QuEChERS extraction method followed by quantification using HPLC/UV-FL was evaluated for deoxynivalenol (DON) and zearalenone (ZEA) determination in natural and parboiled rice and their fractions (bran and husk). The comparison between QuEChERS and partition with acetonitrile extraction showed that the first one was better. It presented higher recovery (91% for DON, 105% for ZEA) wih precision ranging from 1.5 to 18.6%. The limits of quantification were 22.2 g kg-1 for DON and 4.3 g kg-1 for ZEA. DON and ZEA showed higher levels in endosperm of parboiled rice (8 e 111.7 g kg-1, respectively) when compared to natural rice.

Frizzo C.,University of the Rio dos Sinos Valley | Machado V.,University of the Rio dos Sinos Valley | de Oliveira J.V.,Instituto Rio Grandense do Arroz | Fiuza L.M.,University of the Rio dos Sinos Valley
Neotropical Biology and Conservation | Year: 2012

Total and fecal coliforms are bio-indicators of the environmental impact caused by anthropic action and are considered indicators of the microbiological quality of the water. In the cultivation of rice by irrigation much water is used and care in water management is required in order to increase the volume and quality of production while reducing the environmental impact. The objective of this research is to evaluate the quality of the irrigation water used in five rice-growing regions of the State of Rio Grande do Sul during the vegetative and reproductive phases. The results demonstrate that the indices of total and fecal coliforms in the rice field plots of the fields in all the rice producing regions of Rio Grande do Sul evaluated in this study were lower in the reproductive than in the vegetative phases. The irrigation channel presented low indices of fecal coliforms but a higher incidence of total coliforms. The data demonstrated that irrigated rice cultivation can alter the microbiological quality of the water in the plots by its potential capacity of circulating the nutrients with the result that the drainage water presents a smaller quantity of contaminating microbial agents. © 2012 by Unisinos.

Poletto N.,Instituto Federal Of Educacao | Mundstock C.M.,Federal University of Rio Grande do Sul | Grohs D.S.,Instituto Rio Grandense do Arroz | Mazurana M.,Federal University of Rio Grande do Sul
Bragantia | Year: 2011

Rice development is affected by nitrogen, specially its tillering pattern which is determined by number of tillers. Tillers synchronism with main stem is related to leaves emission rate and both traits affect the number of productive culms potential. Tiller esmission and synchronism of leaf development between main stem and tillers were studied in rice plants (cv IRGA 417) cultivated in a hydroponic solution (Hoagland) under three N concentrations (1, 5 e 10 mmol L-1), each with different proportion of N-NH4+ and N-NO3- (100:0; 75:25; 50:50; 25:75). The different proportions under 1 mmol L-1 were similar for tiller number, synchronism, and productive culms. All traits (tiller number, synchronism and productive culms) were negatively affected when higher levels of N-NH4+ ion (5 and 10 mmol L-1 - 100 and 75% of N ions) were supplied to plants. Nevertheless, when N-NO3- ion was present in at least 50% of the solution, the detrimental effects were not found. When N was at 1 mmol L-1, rice plants tolerate N-NH4+ ion presence, independently of the presence of N-NO3- ion. At higher N concentrations, it is necessary at least 50% of N-NO3- ion in order to avoid detrimental effects on tillering.

To verify the relation between aluminum and silicon in the growth of two maize genotypes resistant and sensitive at toxicity aluminum was carried out in the greenhouse a bioensaio involving the treatments presence and absence of aluminum and silicon in corn genotypes. The treatments were compound for solutions of 2.0 mmol L -1 calcium (CaCl 2) without and with aluminum (0.025 mmol L -1 AlCl 3) and silicon (0.14 mmol L -1, to part solution SiO 2). The experiment was carried out for five days and for assess the treatments effect were evaluated root length, silicon, aluminum and calcium concentrations in the shoots and in the roots and the mitotic index of meristematic cells of roots. Silicon reduced the toxic effect of aluminum in corn genotypes as evaluated through root length.

Macedo V.R.M.,Instituto Rio Grandense do Arroz | da Silva A.J.N.,Federal University of Rio Grande do Norte | Cabeda M.S.V.,Federal University of Rio Grande do Sul
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2010

The reclaimation of physically degraded soils has been done using conservationist systems. However, improvement of soil structure makes then very susceptible to intense deformation when bearing compression through mechanization. The compressibility of a Acrisol, physically degraded and reclaimed, collected in the Agricultural Experimental Station of the Federal University of Rio Grande do Sul, in Eldorado do Sul, RS, in two moisture levels, was evaluated with uniaxial compression tests. The soil compression curve, porosity, soil density and resistance to penetration were determined. The physically reclaimed soil samples were more compressible, noteably at higher moisture levels. After applying stresses from 25 to 500 kPa, the reclaimed samples were very similar to the degraded ones. The low resistance to compression showed by the physically reclaimed soil makes evident the difficulty in making compatible the management of conservationist and upgrading structure systems with agricultural mechanization as practiced today. This also strengthens the necessity in finding alternatives to reduce stresses on soils or to make them able to offer higher resistance to compression.

Kalsing A.,Instituto Rio Grandense do Arroz | Vidal R.A.,Federal University of Rio Grande do Sul
Planta Daninha | Year: 2013

The objectives were to estimate the magnitude of the critical density of alexander grass (Urochloa plantaginea) in common bean, in cases where this weed was managed in early stage of crop and occurred reinfestation, and the changes its suffer as a result of different cultivars and variables of alexander grass infestation. Two field experiments were conducted at Eldorado do Sul, RS/Brazil, one cultivated with the bean cultivar UFT-06 (red group) and the other IPR Graúna (black group). The levels of alexander grass infestation were obtained with four residual herbicides, applied at two rates in crop preemergence, and plots with and without weed control. The density, fresh mass and dry mass of alexander grass were evaluated during the critical weed-bean competition period, and the crop yield was evaluated at harvest. The critical density of alexander grass in common bean was not high in this situation (0.4 to 0.7%); however, there may be benefit in weed control according to the level of infestation and cost control. The critical density was always higher for the cultivar IPR Graúna, in relation to UTF-06. The density, fresh mass and dry mass of alexander grass explained adequately the grain yield loss of common bean crop by the nonlinear hyperbolic regression model.

Fraga T.I.,Federal University of Rio Grande do Sul | Carmona F.C.,Federal University of Rio Grande do Sul | Anghinoni I.,Federal University of Rio Grande do Sul | Genro Jr. S.A.,Instituto Rio Grandense do Arroz | Marcolin E.,Instituto Rio Grandense do Arroz
Revista Brasileira de Ciencia do Solo | Year: 2010

Losses of productivity of flooded rice in the State of Rio Grande do Sul, Brazil, may occur in the Coastal Plains and in the Southern region due to the use of saline water from coastal rivers, ponds and the Laguna dos Patos lagoon, and the sensibility of the plants are variable according to its stage of development. The purpose of this research was to evaluate the production of rice grains and its components, spikelet sterility and the phenological development of rice at different levels of salinity in different periods of its cycle. The experiment was conducted in a greenhouse, in pots filled with 11 dm3 of an Albaqualf. The levels of salinity were 0.3 (control), 0.75, 1.5, 3.0 and 4.5 dS m-1 kept in the water layer by adding a salt solution of sodium chloride, except for the control, in different periods of rice development: tillering initiation to panicle initiation; tillering initiation to full flowering; tillering initiation to physiological maturity; panicle initiation to full flowering; panicle initiation to physiological maturity and full flowering to physiological maturity. The number of panicles per pot, the number of spikelets per panicle, the 1,000-kernel weight, the spikelet sterility, the grain yield and phenology were evaluated. All characteristics were negatively affected, in a quadratic manner, with increased salinity in all periods of rice development. Among the yield components evaluated, the one most closely related to grain yields of rice was the spikelet sterility.

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