Accelerated Solvent Extraction of Insecticides from Rice Hulls, Rice Bran, and Polished Rice Grains.

Analysis of pesticide residues in irrigated rice grains is important for food security. In this study, we analyzed accelerated solvent extraction (ASE) conditions for the extraction of thiamethoxam and chlorantraniliprole insecticides from rice hulls, rice bran, and polished rice grains. Several variables, including extraction solvent, extraction temperature, extraction pressure, cell size, static extraction time, and sample concentration, were investigated. The average recoveries of the three matrixes were between 89.7 and 109.7% at the fortification level of 0.75 mg/kg. The optimum ASE operating conditions were acetonitrile (100%) as extraction solvent, extraction temperature of 75°C for rice hulls and 100°C for rice bran and polished rice grains, extraction cell pressure of 10.3 MPa, 22 mL cell size, and two extraction cycles. The total extraction time was approximately 25 min. The extracted volume was evaporated to dryness and the residues were redissolved in 2 mL acetonitrile after 1 min of vortex-shaking. Thiamethoxam and chlorantraniliprole were analyzed by ultra-HPLC with tandem MS. In conclusion, ASE in rice hulls, rice bran, and polished rice grains offers the possibility of a fast and simple method for obtaining a quantitative extraction of the studied pesticides.

Residues of thiamethoxam and chlorantraniliprole in rice grain.

Thiamethoxam and chlorantraniliprole insecticides have been important tools for controlling pests in rice. However, food safety issues related to pesticide residues are important to consider with a food crop such as rice. Therefore, the objective of this study was to analyze thiamethoxam and chlorantraniliprole residues in rice hull, bran, and polished rice grains. The study was conducted during the 2012 cropping season at the Texas A&M Agrilife Research, David R. Wintermann Rice Research Station, near Eagle Lake, TX, USA. Rice was planted on May 5, 2012, using the cultivar 'Presidio'. Pesticide applications were performed at 5, 15, 25, and 35 days after flowering (DAF) using 1 and 2 times the recommended rate of 30 g active ingredient (ai) ha(-1) for thiamethoxam and 30 g ai ha(-1) for chlorantraniliprole. Sequentially, two treatments using the insecticides at recommended rate were applied at 5 and 25 DAF and at 5, 25, and 35 DAF. Insecticide residues were analyzed in different sample fractions: rice hull, bran, and polished rice grains. The samples were subjected to extraction using an accelerated solvent extraction (ASE) technique. Sample aliquots were analyzed using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), with a limit of quantification (LOQ) of 5 × 10(-5) mg kg(-1). Residues of thiamethoxam and chlorantraniliprole were detected in rice hull, bran, and polished rice grains, and the quantified values were greater in hull and in rice bran.

Brazilian university technology transfer to rural areas / Transferência de tecnologia de universidades brasileiras na área rural

In agriculture, there is a difference between average yield obtained by farmers and crop potential. There is technology available to increase yields, but not all farmers have access to it and/or use this information. This clearly characterizes an extension and technology transference problem. There are several technology transfer systems, but there is no system to fit all conditions. Therefore, it is necessary to create extension solutions according to local conditions. Another rural extension challenge is efficiency, despite continuous funding reductions. One proposal that has resulted from extension reform worldwide has suggested integration between the public and private sectors. The public universities could play the role of training and updating technical assistance of human resources, which is the one of the main aspects that has limited technology transfer. The objective of this study was to identify approaches to promote technology transfer generated in Brazilian public universities to rural areas through literature review. An experimental approach of technology transfer is presented here where a Brazilian university extension Vice-chancellor incorporates professionals from consolidated research groups according to demand. In this way, public universities take part of their social functions, by integrating teaching, research, and extension.

Em agricultura, há diferenças entre a produtividade média obtida pelos produtores e o potencial produtivo dos cultivos. Há informação tecnológica disponível para aumentar a produtividade, mas nem todos os produtores têm acesso e/ou usam a informação. Isso caracteriza claramente um problema de extensão e transferência de tecnologia. Há vários sistemas de transferência de tecnologia, mas, como não há sistema que se ajuste a todas as condições, é necessário criar alternativas adequadas às condições de cada local. Outro desafio da extensão rural é ser eficiente, apesar da contínua redução de recursos. Uma proposta advinda das constantes reformas na extensão verificada ao redor do mundo é o trabalho integrado entre a iniciativa privada e o poder público. A universidade pública contribuiria para o treinamento e a atualização dos recursos humanos envolvidos com assistência técnica, apontado como um dos aspectos limitantes na transferência de tecnologia. O objetivo deste estudo foi identificar, por meio de revisão bibliográfica, alternativas de promover a transferência de tecnologias geradas nas universidades públicas brasileiras para a área rural. Assim, é apresentada uma proposta de transferência de tecnologia a ser gerenciada pelas Pró-reitorias de extensão das universidades brasileiras, tendo como base os grupos consolidados de pesquisa, nos quais poderiam ser incorporados outros profissionais de acordo com a necessidade. Dessa forma, a universidade pública recuperaria parte da sua função social, integrando ensino, pesquisa e extensão.

Profundidade de localização do herbicida imazetapir + imazapique no solo sobre a fitotoxicidade em de plantas de arroz não resistente / Depth of placement of the herbicide imazethapyr + imazapic in soil profile on non-tolerant rice injury

Os herbicidas imazetapir e imazapique, usados em cultivares de arroz Clearfield®, possuem alta persistência e mobilidade no solo, ocasionando danos em genótipos de arroz não resistentes cultivados em rotação. Tais herbicidas podem lixiviar e atingir maiores profundidades ao longo do perfil. Esse posicionamento em profundidade pode ser um fator de seletividade e explicar parcialmente os diferentes resultados encontrados na literatura sobre o efeito residual do herbicida no solo. O objetivo do estudo foi avaliar o efeito da profundidade de localização no solo e da mistura formulada pelos herbicidas imazetapir e imazapique (75 e 25g e.a. L-1) na fitotoxicidade em genótipos de arroz não resistentes. Nesse sentido, foram conduzidos dois experimentos em solo com 15 por cento de argila e 1,2 por cento de matéria orgânica, em casa-de-vegetação, no campus da Universidade Federal de Pelotas (UFPel), em Pelotas, Rio Grande do Sul (RS). O experimento I consistiu de estudo preliminar visando a determinar a profundidade máxima de localização do herbicida no solo que causa danos ao arroz não resistente, e o herbicida foi alocado nas profundidades de 0, 5, 10, 20, 30, 50 e 70cm. O experimento II também consistiu na alocação do herbicida em profundidades ao longo do perfil do solo de 3, 6, 9, 12, 15 e 18cm. As variáveis analisadas foram fitotoxicidade, massa da matéria seca e estatura das plantas. O herbicida resultante da mistura formulada de imazetapir com imazapique localizado próximo à superfície do solo causa danos intensos em plantas de arroz não resistente, porém, quando alocado em profundidades maiores que 20cm da superfície do solo, não prejudica o desenvolvimento de genótipos de arroz não resistentes a essa mistura de herbicidas.

The herbicides imazethapyr and imazapic, used in Clearfield® rice, have high mobility and persistence in the soil, causing injury to non-resistant rice grown in rotation. These herbicides can leach and reach greater depths along the profile. This positioning can be a in-depth selectivity factor and partially explain the different results found in literature about carryover of imidazolines. To understand this effect, this study had the objective of to evaluate the effect of the positioning of the mixture of imazethapyr and imazapic (75g ai L-1 and 25g ai L-1) on the injury to non-resistant rice crop. Two experiments were carried out in soil with 15 percent clay and 1.2 percent organic matter in a greenhouse at the Universidade Federal de Pelotas, Pelotas, RS, Brazil. Experiment I consisted of a preliminary study to verify the location depth of the herbicide in the soil profile that causes injury to rice non-tolerant rice, and the herbicides has been allocated at depths of 0, 5, 10, 20, 30, 50 e 70cm. Experiment II also consisted in the allocation of herbicide at depths in the soil profile of 3, 6, 9, 12, 15 and 18cm. The variables were visual plant injury, plant shoot dry weight and plant height. The formulated mixture of imazethapyr + imazapic located near the soil surface cause injury to non resistant rice plants but when allocated at depths greater than 20cm of the soil surface does not affect the development of non-resistant rice.

Adsorption and desorption of atrazine, desethylatrazine, deisopropylatrazine, and hydroxyatrazine in vegetated filter strip and cultivated soil.

Adsorption and desorption of atrazine and its metabolites in vegetated filter strip soil (VFS) has not been evaluated, yet these data are needed to predict the transport of these compounds through the VFS. Adsorption and desorption parameters for atrazine, desethylatrazine (DEA), deisopropylatrazine (DIA), and hydroxyatrazine (HA) were compared between a cultivated Houston Black clay (CS) and an adjacent 12-year-old VFS established in a mixed stand of bermudagrass [Cynodon dactylon (L.) Pers.] and buffalograss [Buchloe dactyloides (Nutt. Engelm)]. Adsorption and desorption isotherms were determined by batch equilibrium. The evaluated chemical and physical properties of the VFS and CS were similar with the exception of a 1.7-fold increase in the organic carbon content of the VFS. Adsorption and desorption coefficients for atrazine were at least 59% higher in VFS than in CS. The adsorption coefficient for HA was 48% higher in VFS compared with CS, but desorption was not statistically different between soils. Adsorption and desorption coefficients for DEA and DIA were not statistically different between soils. The predicted order of mobility in CS is HA < atrazine = DIA = DEA. In VFS, the predicted order of mobility is HA < atrazine = DIA < DEA. These data indicate that the higher organic carbon in VFS will likely retard the transport of atrazine and HA to surface and ground waters; however, the transport rates of DEA and DIA will be similar between soils.