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En la actualidad, uno de los elementos que ha cobrado protagonismo en la optimización de cultivos es el Silicio (Si), un mineral que tradicionalmente ha sido subestimado, sin embargo, juega un papel vital en el bienestar de las plantas. El objetivo de este estudio fue evaluar el efecto de diferentes fuentes y dosis foliares de Si sobre el desarrollo y asimilación de nutrientes en el cultivo de pimiento. El diseño experimental corresponde a un DCA. Los resultados arrojaron que no hubo diferencias significativas en las variables biométricas, como la altura de la planta, el diámetro del tallo y el número de hojas, flores y frutos, entre los tratamientos de fuentes y dosis de Si. Esto sugiere que las dosis de Si evaluadas no tuvieron un efecto sustancial en el crecimiento general de las plantas de pimiento. Sin embargo, se observaron efectos significativos del Si en la química foliar de las plantas. Los tratamientos con Si mostraron concentraciones más bajas de nitrato y potasio en comparación con el grupo de control. Además, se registraron concentraciones más altas de sodio en algunos tratamientos con Si y los valores de pH tanto en el área foliar como en tejidos vegetales se disminuyeron en los tratamientos con Si 1000 y K4(SiO4). Estos hallazgos indican que el Si puede influir en la química foliar de las plantas de pimiento. En cuanto a la salinidad y la CE, se encontraron diferencias estadísticas en los valores de los extractos de hojas y de tallo más peciolo.

En el Perú, el plátano o banano, es la fruta cultivada más importante. En Tumbes se cultivan 4 800 hectáreas, parte de esas áreas se encuentran en el valle de Zarumilla. Uno de los problemas fitosanitarios, es la sigatoka negra (Micosphaerella fijiensis Morelet), que disminuye el área foliar de las plantaciones, con efectos sobre los rendimientos. El objetivo fue evaluar el efecto de tres dosis de Silicio en los parámetros de rendimiento y control de la citada enfermedad en Musa spp., bajo condiciones de campo en dicho valle. El diseño experimental empleado fue bloques completamente al azar (BCA). De acuerdo con los estudios realizados se concluyó que, en los parámetros de rendimiento, el silicio no presentó efecto en la circunferencia del pseudotallo, área foliar, el número de manos por racimo y peso del racimo, pero si hubo efectos en el número de hojas al momento de la floración, al momento de la cosecha y en el peso de dedos del banano. En cuanto al efecto del silicio en el control de “sigatoka negra” se logró disminuir el índice de daño en un 17,66% en el tratamiento S3 (150 kg/ha) en comparación con el testigo (0 kg/ha) que se obtuvo 28,22%.

Undoped CeO2, co-doped and tri-doped CeO2 with Si, Si-Al and Si-Fe, were prepared by sol-gel method. Nanoparticles with an average crystal size of 2-10 nm, were obtained and structurally characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Powders were compacted by uniaxial pressure and sintered in air at 1250 °C to obtained sintered pellets. The different compositions maintained the cerianite crystal structure, implying that dopant elements enter in the structure forming a solid solution, although some segregation was observed by SEM and TEM analysis in pellets. The undoped CeO2 material reached a relative density of 0.95% at 1250°C while doped samples presented variations in this value and grain size and relative density, clearly attributed to doping. According to these results, these materials could have potential applications in solid oxide fuel cells, electrodes and sensors. [ABSTRACT FROM AUTHOR]

Soursop cultivation can be affected by a variety of pests that affect its normal development, measures to control pests especially in flowers and fruits are necessary. The use of diatomaceous earth is an alternative for pest management; however, its control potential is unknown. For this reason, the objective of the research was to evaluate the effect of diatomaceous earth on the control of cottony cochineal and sooty mold in fruits of the soursop crop. A randomized complete block design (DBCA) with seven treatments and three repetitions was used. The treatments evaluated were diatomaceous earth (SIO-DEM +) in doses of 2.00; 4.00; 6.00; 8.00; 10.00 and 12.00 kg ha-1 and control (without application). The variables evaluated were, percentage of incidence of mealybugs, degree of severity of sooty mold and fruit development (length, thickness and weight). The results obtained showed that the percentage of incidence of cottony mealybug using the doses of 10.00 kg ha-1 and 12 kg ha-1 decreased the incidence of the pest by more than 40%. The severity of sooty mold damage in soursop fruits under the effect of different doses of diatomaceous earth decreased in grade 3 - 2 with the treatments T5 (10.00 kg ha-1) and T6 (12.00 kgha-1). [ABSTRACT FROM AUTHOR]

La enfermedad conocida como mancha de asfalto (Phyllachora maydis) afecta al cultivo de maíz (Zea mays). Esta enfermedad causa lesiones en las hojas que al progresar pueden ocasionar la muerte de la planta. Existen diferentes métodos para evaluar el progreso de una enfermedad en las plantas. Generalmente, se utilizan escalas de evaluación visual; sin embargo, su uso es bastante subjetivo. El procesamiento de imágenes ha sido utilizado como una alternativa para la evaluación de enfermedades. Este método evita sesgos y errores durante las evaluaciones. El objetivo de este ensayo fue utilizar el aplicativo telefónico Leaf Doctor como una alternativa a la evaluación de la enfermedad producida por P. maydis. Para el experimento se utilizó un diseño de bloques completamente al azar. Se sembraron tres variedades de maíz y se evaluó el nivel de tolerancia a la mancha de asfalto al ser tratadas con diferentes dosis de silicio. Las diferentes dosis de silicio no reducen la enfermedad, sin embargo, fue posible determinar aumento de la producción de maíz en dosis de silicio de 252 kg ha-1. Los resultados indican que el programa puede considerarse como una alternativa eficiente para evaluar la mancha de asfalto debido a la alta correlación con la escala de evaluación visual (R2: 0.77-0.94). La variedad más resistente a la enfermedad fue INIAP-551.

Copyright of Revista Agrotecnologia is the property of Universidade Estadual de Goias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Las nanopartículas de silicio (SiNPs) tienen características intrínsecas que le confieren biocompatibilidad, alta estabilidad química-térmica y amplia área superficial. Esta última cualidad le permite anclar una gran cantidad de moléculas en su superficie, en las cuales se han incluido nucleótidos, proteínas y una diversidad de compuestos químicos con potencial uso en la agricultura. En este contexto, este trabajo describe brevemente aspectos fundamentales sobre las SiNPs, además de presentar una compilación de los últimos trabajos relacionados con el uso de SiNPs y su efecto en diferentes cultivos. Finalmente, se pone en perspectiva un análisis del panorama actual y las capacidades científicas relacionadas con la innovación nanotecnológica enfocadas al sector agrícola del país.

Blackberry gray mold, induced by Botrytis cinerea, is a fruit disease that causes important economic losses. The present study evaluated nine fungicides belonging to different chemical groups, alone and in combination with potassium silicate, using the dose recommended on the label for the control of B. cinerea in the field. The incidence and severity of the disease were evaluated, as well as the degrees Brix, silicon concentration, and yield. The experiment was carried out twice. Incidence and severity percentages were converted to area under the disease progress curve (AUDPC). Combined with potassium silicate, the fungicide azoxystrobin significantly reduced incidence and severity, showing the lowest percentages in the last evaluation of these variables. In the first repetition, the incidence and severity values were 4% (AUDPC = 1320) and 0.1% (AUDPC = 298.5), respectively. In the second, 3% (AUDPC = 1099) and 0.1% (AUDPC = 214.5) respectively. The concentration of soluble solids and fruit yield increased (12.4 and 13.6 t ha-1 in the first and second repetition, respectively). The results indicate that potassium silicate enhances the effect of fungicides under field conditions and can thus be considered a management alternative against the gray mold disease in blackberries. [ABSTRACT FROM AUTHOR]

Siho is an archaeological site located in the Northern Maya Lowlands, where a number of grinding tools have been documented, mostly metates made with local limestone that has petrological characteristics (physical and chemical) which may indicate a particular geological origin. The statistical treatment of data extracted by X-ray fluorescence allows us to discern limestone materials from different geological formations, based on the quantity of silicon (Si) and/or calcium (Ca) in the sample. This data shows a link between the limestone of the Sihó metates and the rocks from the geological formation known as Carrillo Puerto located in the Yucatan peninsula. Furthermore, the comparison by mean thin sections between geological and archaeological materials has been useful to characterise and identify lithic materials used to fabricate the metates. The complementarity between both archaeometrical techniques, together with ethnographic, historical and archaeological documentation, provide us with information that suggests an immediate exploitation of the limestone rocks used to make the metates and brings us closer to a better understanding of the quarrying strategies practiced by the ancient Mayans of Sihó. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A suitable combination of organic sources of nutrients can allow an adequate growth, yield of the strawberry crop, and decrease the use of chemical fertilizers to the benefit of the environment and consumers. Likewise, silicon can help plants to withstand adverse environmental, biological, and edaphic conditions, increasing and improving production quality. Therefore, the objective of this study was to evaluate the effect of three sources of organic fertilization: one of animal origin (fish); one of vegetable origin (corn), and one of animal and vegetable origin (fish - corn) plus a chemical treatment such as control (Steiner), with three silicon concentrations of 0, 15 and 20 ppm. Growth parameters, physiological parameters, as well as nutraceutical performance and quality were evaluated in strawberry fruits of the Camino Real cultivar, under a completely randomized design with factorial arrangement (4 x 3). The results of vegetative growth and physiological parameters of the treatments with organic fertilization showed statistically equal values to the control treatment, likewise for the yield and nutraceutical quality. The addition of silicon to the doses studied did not cause effects on any of the variables studied. The results suggest that it is totally feasible to replace chemical fertilization with organic, obtaining identical results. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Actualmente ha crecido el interés por la fabricación y caracterización de nanoestructuras de silicio, entre las que se incluye nanohilos, pilares, tubos, conos, partículas, etc; existiendo diversos métodos para generar estas nanoestructuras entre los que se puede mencionar la ablación con láser, la descomposición por evaporación térmica, la deposición de vapor químico, entre otros. Las propiedades que exhiben estas estructuras las hacen atractivas para aplicaciones en biomedicina y biotecnología. Estos materiales representan herramientas con un potencial elevado para mejorar las técnicas de diagnóstico y tratamiento de condiciones biológicas especiales. Esta revisión bibliográfica pretende resumir algunos aspectos importantes del diseño fisicoquímico de estos nanomateriales, además de consideraciones toxicológicas de biocompatibilidad, biodistribución y la dinámica celular. Finalmente, se hace énfasis en algunas aplicaciones biomédicas importantes, especialmente en terapia génica, liberación controlada de fármacos, imagenología y biosensores.

The present work developed at the University of Tolima (Ibagué, Tolima, Colombia) was aimed to evaluate the effect of silicon as an inducer of systemic resistance and the antagonism of T. viride against the vascular wilt of hybrid tomato Santa Clara (S. lycopersicum L.) caused by F. oxysporum f.sp. lycopersici. The inducing effect of silicon on the tomato defense response on epidemiological parameters of the disease and the activity of the Polyphenoloxidase (PPO) enzyme were evaluated through biochemical analysis. A factorial design with 8 treatments and 12 replicas was used. A 47 % reduction in foliar severity was found in plants treated with silicon and T. viride with respect to plants that were not treated with silicon. In addition, an increase in the enzymatic activity of Polyphenoloxidase (PPO) was found in plants that were treated with silicon and not inoculated with T. viride, the mean of this treatment being 2.29 U/mg of protein compared to those they were not treated with silicon and inoculated and not inoculated with T. viride, the average of this treatment being 0.36 U/mg of protein. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the effect of bean seed coating with different doses of silicon (Si) on their physical, physiological and sanitary attributes, as well as to determine the amount of nutrients absorbed in the seedlings. BRS Expedito beans, 2014/15 harvest, were used, with an initial germination of 82%. Being used as a source of Si, calcium and magnesium silicate powder (Agrosilício®) (Si: 10.53%; Ca: 25.00%; Mg: 7.00%; Fe: 10.20%; Cr: 4, 48%; Mn: 1.72%; Ti: 0.69%; S: 0.52%; K: 0.35%), previously sieved, with a density of 1.30g / cm³. The treatment consisted of covering bean seeds, in the equivalent doses of 0, 45, 90, 135 and 180g Si 100kg-1 of seeds, which corresponded to 0; 427.3; 854.7; 1,282; 1.709g of the product for 100kg-1 of seeds. The increase in doses of up to 116g of Si 100kg-1 of seeds positively influences the expression of vigor, providing a superior development of seedlings, as well as an increase in the concentration of Si in the leaves and root Ca. Doses other than Si do not control pathogens associated with seeds. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this research was to evaluate the effect of treating oranges with potassium chloride (KCl), potassium hydroxide (KOH) and potassium silicate (K2O3Si) for green mold caused by Penicillium digitatum. The experimental design was completely randomized with five treatments and four replications, each with twenty fruits. For the experiment, the fruits were washed, superficially disinfected and pierced with a needle (2–3 mm deep). After 24 hours, the fruits were treated with inorganic salts or distilled water (control) and, 2 hours later, inoculated with 15 μL of P. digitatum spore suspension. Green mold incidence, rate of lesion expansion, lesion size and sporulation area were evaluated at 96, 120 and 245 ha. At 245 hours after inoculation (hai), the KOH and K2O3Si (50 g.L-1) treatments were the most effective, affecting all evaluated variables and reducing the disease incidence by 80% and 36%, respectively, compared to the control. However, the KOH treatment caused wrinkling and dehydrated the peel, affecting the visual quality of the fruits. In conclusion, among the tested inorganic salts, the K2O3Si treatment (50 g.L-1) reduced the green mold in the citrus without negatively effecting fruit appearance, which indicates that this treatment is an option as a complementary measure to manage the disease.

Trabalhos de pesquisa no Brasil e em outros países, com a utilização de silicato de cálcio, vem mostrando resultados promissores na cultura da cana- de- açúcar. Este trabalho objetivou avaliar o efeito residual da aplicação do silicato de cálcio como material corretivo de acidez do solo, nos atributos químicos do solo e na produtividade da primeira soqueira de cana-de-açúcar. O trabalho foi desenvolvido, em condições de campo, na Fazenda Escola da Anhanguera de Dourados-MS, com a variedade SB803250. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições. Os tratamentos foram constituídos de doses distintas de silicato de cálcio (0, 700, 1400, 2800, 5600 kg ha-1). No solo, a amostragem foi realizada aos 24 meses após a aplicação do silicato de cálcio, nas camadas de 0-0,2- e 0,20-0,40 m de profundidade, determinando os atributos químicos para fins de fertilidade do solo e a produtividade da cana-soca. O silicato de cálcio promoveu efeito residual benéfico nos atributos de acidez do solo após 24 meses da aplicação. A aplicação do silicato de cálcio, em pré-plantio, promoveu efeito residual positivo na produtividade da soqueira da cana-de-açúcar.

Se realizaron aplicaciones de distintas fuentes de Si y Ca foliar en vivero de palma aceitera y se evaluó el efecto de la severidad del Complejo de Necrosis Foliar (CNF) en el Pacífico Sur de Costa Rica. Se utilizaron 4 fertilizantes foliares de Ca, 3 fuentes de Si y una fuente de Ca con fitoalexinas. El diseño experimental fue de bloques completos al azar con 9 tratamientos y 4 repeticiones. Se evaluó a los 85, 130, 175, 220, 265 y 300 días después de siembra (dds) el crecimiento morfológico de las plantas y el porcentaje de severidad de CNF en las hojas. A los 175, 220, 265 y 300 dds se evaluó la concentración foliar de N, P, K, Ca, Mg, S, Fe, Zn, Mn, Cu, B y Si. Las aplicaciones de Si y Ca foliar no mostraron un efecto significativo en la tolerancia al CNF en el tiempo. No se encontraron diferencias significativas en las concentraciones foliares de Si y Ca. El tratamiento SupCu proporcionó mayor concentración de Cu en las plantas de palma aceitera y redujo significativamente la severidad de CNF. Además, se encontró que productos con contenidos de K y P en forma de fosfitos pueden aumentar el vigor en las plantas. Se concluyó que los fertilizantes foliares con Ca y Si no fueron eficaces para el control del CNF y que productos con Cu pueden aumentar la tolerancia a este complejo.

Se evaluó el efecto de diferentes fuentes de Si en la severidad de enfermedades foliares (CNF) en plantas de vivero de palma aceitera (Elaeis guinensis) en el Pacífico Sur de Costa Rica. Las fuentes de silicio consistieron en la aplicación de 30 g de SiO2 por bolsa de 20,4 L de 2 fuentes de serpentinas (Simag y SMg), una fuente de diatomitas (SiF), una fuente soluble (SKH) y 177 g por bolsa de SiO2 de un feldespato (Llane) mezclado en un Inceptisol éutrico. El diseño experimental fue de bloques completos al azar con 6 tratamientos y 4 repeticiones. Se evaluó a los 85, 127, 176, 219, 261, y 304 dds el crecimiento de las plantas y % de severidad de CNF. Además, se realizaron análisis químicos de suelos y foliares en el tiempo, se evaluó el peso seco de plantas y se calculó la absorción de nutrimentos. Se encontró que el tratamiento SiF mostró mayor tolerancia a CNF significativamente (a:0,05) en comparación al testigo, mientras que la fuente Simag mostró un mayor crecimiento. El Si presentó mayor absorción en Simag, test, SMg, SiF y fueron significativas diferentes con respecto al SKH y Llane. El SKH en suelo fue el único tratamiento que aumentó los niveles de Si por arriba de los 200 mg.l-1. A los 300 dds, el análisis de componentes principales correlacionó la severidad con las concentraciones de Ca en el suelo y mostró un comportamiento inverso a los contenidos de Zn, K, P, Mn y en el tiempo. Se concluye que el Si en este suelo no presentó un efecto directo sobre el control de CNF, pero la fuente de diatomitas (SiF) mostró mayor tolerancia, debido a que la enmienda facilita la absorción de micronutrimentos (Zn) al mejorar la nutrición de la planta. Asimismo, se encontró que la fuente SKH logró aumentar las concentraciones de Si en el suelo.

Sclerotium rolfsii, a widespread fungus in tropical and subtropical regions, is a phytopathogen that affects a large number of cultivated and wild plants-e.g. Brachiaria species-, causing plant damping-off events. Current disease control strategies include chemical treatment of seeds, genetic resistance and crop rotation. Compared to synthetic agrochemicals, silicon may induce plant resistance. This study examined the efficiency of calcium silicate in the coating of Brachiaria seeds on the incidence of the disease during plant germination and establishment. The experiment consisted of six Brachiaria brizantha seed-coating treatments involving different calcium silicate and sand proportions and two controls. The fungus was inoculated at three different times in relation to seed sowing: inoculation at sowing (IN0); inoculation 10 days after sowing (IN10); inoculation 20 days after sowing (IN20); and no inoculation (control). Radicle emergence, germination, abnormal seedlings, damped-off seedlings and dead seeds were evaluated. Increase in the germination rate of B. brizantha cv. MG5 seeds coated with calcium silicate was observed, which showed protective effect against the incidence of S. rolfsii, directly reflecting in lower damping- off percentages. The application of calcium silicate as coating provided protection to MG5 seeds and plants inoculated with S. rolfsii. [ABSTRACT FROM AUTHOR]

Silicon is a beneficial nutrient for the growth and production of many plant species, including tomatoes. The objective was to evaluate the influence of calcium silicate on the morphophysiological characteristics of tomatoes and the absorption of silicon, calcium, and magnesium. The experiment was conducted in a protected environment from August to December 2017, in a random block design, in a 2 x 5 factor scheme, with four repetitions. The first factor consisted of two hybrids (Ivety and Natalia) and the second factor by doses of calcium silicate (0, 150, 300, 450 and 600 kg ha-1). The fruits were evaluated for number of fruits per plant, longitudinal and transversal diameter, average fruit mass, commercial, noncommercial, and total productivity. The plants were evaluated for number of leaves, stem diameter, plant length, leaf area, membrane integrity damage, lignin content, stem and leaves dry mass, silicon accumulation and content, calcium, and magnesium contents in the leaves and in tomato fruits. The morphometric characteristics of Ivety and Natalia tomato hybrids were not altered by increasing doses of calcium silicate. The increased doses of calcium silicate influenced the non-commercial productivity of the tomato fruits, showing a reduction of this with the increased doses. Calcium silicate influenced differently in each hybrid, and it is worth noting that these results may vary in terms of genetic material and cultivation environment. [ABSTRACT FROM AUTHOR]

The objective of the research was to evaluate the residual effect of the seeds treatment with fungicide and silicate fertilizer in the control of brown spot in the vegetative stage of the barley plant. The experiment was a two-way factorial with four seed treatments (ST): control (distilled water), fungicide (triadimenol), silicate fertilizer and the fungicide + silicate fertilizer and three periods of 30, 45 and 60 days after emergence (DAE). Barley plants were inoculated with a spore suspension of Bipolaris sorokiniana. The disease severity assessment over time was used to calculate the area under the brown spot progress curve (AUCPBS). At 30 DAE, fungicide treatment was the most efficient with reduction of 64% in the AUCPBS, followed by silicate fertilizer with 56%. The mixture also reduced AUCPBS, but with lower efficiency than isolated products. [ABSTRACT FROM AUTHOR]

Copyright of Agro Productividad is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Momento: Revista de Física is the property of Universidad Nacional de Colombia, Departamento de Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aluminum foils with a thickness of less than 200 μm are used in numerous applications, such as the manufacture of different products, disposable packaging, radiator fins and blisters. These applications require both good corrosion resistance and mechanical strength. Iron present in 1xxx and 8xxx aluminium alloys forms two main secondary phases: Al3Fe and α-AlFeSi, the last one as dispersoids, altering the kinetics of recrystallization and therefore giving rise to excellent strength and elongations after annealing. Silicon and iron form phases such asO-Al13 Fe4 (monoclinic), Al6Fe (orthorhombic), Al12Fe3Si and Al3Fe, which are controlled during solidification to improve mechanical properties. Manganese present in 3xxx alloys may form two main phases Al6 (Mn, Fe) and α-Al12(Fe, Mn)2Si, but Al12(Fe, Mn)3Si may also be present when silicon is added so many properties are strongly dependent on both type and particles shapes, Thus, microstructure must be well controlled in the solidification and subsequent processes. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max) is a crop of high economic power in the world, being used to produce vegetable oil, as well as a source of food for animals and humans. Recent research indicates that nutrient application in the seed stage contributes to an early and productive development of crops. Since silicon (Si), as a nutrient for plants, acts in the cellular structure and the formation and performance of plant architecture, the aim of this study was to evaluate the influence of silicon application via seeds on the initial growth of three soybean cultivars. The experimental design was a randomized block. The treatments were replicated three times and distributed in a 3×5 factorial scheme, composed by three soybean cultivars (C1 - FTR 1186 IPRO, C2 - FTR 1192 IPRO and C3 - FTR 3190 IPRO) and five silicon doses (0, 30, 60, 90 and 120 g per 100 kg of seeds). The data were submitted to ANOVA by F-test and polynomial regression analysis for the silicon doses; the cultivars response was evaluated through the Tukey mean test. The treatment of soybean seeds with silicon did not positively influence the root dry mass of the FTR 1192 IPRO, nor the root length and root diameter of the FTR 1186 IPRO. The application of silicon did not influence the FTR 3190 IPRO. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Ciencias Hortícolas is the property of Revista Colombiana de Ciencias Horticolas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), is an invasive pest of grain sorghum, Sorghum bicolor (L.) Moench (Poaceae). Since its first outbreak in sorghum in 2013, severe infestations have spread throughout the southern USA, causing major economic losses. Whereas insecticide applications can mitigate some of the pest's impacts, a sustainable ecology-based management program is needed to reduce reliance on chemical control. Two greenhouse assays examined the influence of selected host plant characteristics on M. sacchari life table parameters. We studied the effects of silicon (rates equivalent to 0 and 3,360 kg silicon per ha) and nitrogen (rates equivalent to 0, 110, and 224 kg nitrogen per ha) on M. sacchari growth and reproduction on a susceptible cultivar (SP 7868) in 2 phenological stages (5-leaf stage and boot stage). A second experiment examined the same silicon and nitrogen treatments on resistant (DKS 37-07) and susceptible (DKS 38-88) cultivars of grain sorghum. We calculated M. sacchari life table parameters including the intrinsic rate of increase, finite rate of increase, doubling time, and mean generation time for each treatment. Aphid population growth parameters were greater for plants in the 5-leaf stage than in the boot stage. In both experiments, nitrogen fertilization had a positive effect on M. sacchari fecundity, but effects of nitrogen on other parameters were less consistent. Silicon had a negative effect on life table parameters on sorghum plants in the boot stage, but effects were not consistent across treatments. Sorghum cultivar DKS 37-07 showed a high level of resistance, because no aphids survived to adulthood. These results suggest that resistant sorghum cultivars and nitrogen management could have a role in integrated pest management of M. sacchari. [ABSTRACT FROM AUTHOR]

Copyright of Engenharia na Agricultura is the property of Engenharia na Agricultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to evaluate the process of acid leaching, in HCl, for purification of silicon metal, obtained by magnesiothermic reduction of silica and promote greater removal of impurities. The reaction product formed is a powder which is physically and/or chemically bound, with approximately 75% of MgO and approximately 25% of silicon metal, among other elements. Acid leaching is an technique used in the solubilization of oxides by an acid solvent. The silicon metal with purities up to 94% can be obtained in one step. Thus, it has been tested the effect of the following concentration of hydrochloric acid HCl (1, 2, and 3 M), temperature (50, 65, and 80° C) and time (60, 90 and 120 min). The leaching kinetics was studied under non-isothermal condition. After the treatments, it was shown that concentration is the main effect of leaching. In some analyses, it was possible to convert up to 76%, i.e., 99.66% of MgO has been extracted. [ABSTRACT FROM AUTHOR]

Las aleaciones utilizadas para el revestimiento de superficies sometidas a baja o moderada abrasión son altamente complejas. Con la finalidad de buscar una alternativa más simple, en el presente trabajo se estudian tres revestimientos, aplicados utilizando electrodos con diferentes composiciones basadas en fundiciones hipoeutéticas Fe-Si-V-C con 3,2 % de C, V entre 0,47 y 1,57 %, y Si entre 2,30 y 3,82 %. Los revestimientos resultantes fueron estudiados utilizando técnicas de microscopía óptica (MO), microscopía electrónica de barrido (MEB), difracción de rayos X (DRX) y dureza. Los resultados mostraron que para contenidos de Si y V bajos, se obtuvo la dureza más elevada (64 HRC), derivada de una microestructura donde predominan la martensita y la austenita. Al aumentar las cantidades de estos elementos en la aleación, se obtuvo mayoritariamente perlita, con zonas eutécticas y carburos de V distribuidos en ellas, originando una disminución de la dureza hasta 57 HRC. Por lo tanto, utilizando contenidos de Si y V bajos (cercanos a 2,30 % de Si y 0,47 % de V), los electrodos basados en el sistema aleante Fe-Si-V-C pueden ser una alternativa para revestir superficies sometidas a desgaste abrasivo bajo o moderado.

Se evaluó el uso de fertilizantes líquidos con Si, Ca o Mg sobre el crecimiento del sorgo (Sorghum bicolor) en un Ultisol bajo invernadero. Se utilizaron 2 silicatos de potasio, carbonato de calcio y óxido de magnesio, todos en líquidos aplicados al suelo en dosis de 2 y 4 ml.pote-1, y un testigo, en un diseño irrestricto al azar con 9 tratamientos y 4 repeticiones. Las variables de crecimiento, evaluadas 45 días después de siembra, fueron peso seco de raíz y de parte aérea. Se realizó un análisis de suelos y de planta al final del ensayo. Las aplicaciones de Ca y de Mg incrementaron de manera significativa el crecimiento y la absorción de nutrimentos del sorgo. El carbonato de calcio promovió los valores más altos de biomasa seca y de absorción de N, P, Ca, S, Cu, Zn, Mn y B. Las fuentes de Si no tuvieron efectos significativos sobre la biomasa del sorgo, a excepción del silicato de K con Ca y Mg en dosis de 4 ml.pote-1, que además produjo un incremento significativo en la absorción de K. El carbonato de calcio y el óxido de magnesio incrementaron significativamente el pH, disminuyeron la acidez y el Al intercambiable, y aumentaron los contenidos de Ca o Mg en el suelo.