Effects of soil and foliar application of soluble silicon on mineral nutrition, gas exchange, and growth of potato plants

Silicon can alleviate biotic and abiotic stresses in several crops, and it has beneficial effects on plants under nonstressed conditions. However, there is still doubt about foliar-applied Si efficiency and Si effects on mineral nutrition, physiological processes, and growth of potato (Solanum tuberosum L.) plants under wellwatered conditions. The objective of this study was to evaluate the effect of soil and foliar application of soluble Si on Si accumulation, nutrients, and pigments concentration as well as gas exchange and growth of potato plants. The experiment was conducted under greenhouse conditions in pots containing 35 dm3 of a Typic Acrortox soil. The treatments consisted of a control (no Si application), soil application of soluble Si (50 mg dm-3 Si), and foliar application of soluble Si (three sprays of 1.425 mM Si water solution, prepared with a soluble concentrate stabilized silicic acid), with eight replications. Both soil and foliar application of Si resulted in higher Si accumulation in the whole plant. Foliar application of Si resulted in the greatest Si concentration in leaves, and soil application increased Si concentration in leaves, stems, and roots. Silicon application, regardless of the application method, increased leaf area, specific leaf area, and pigment concentration (chlorophyll a and carotenoids) as well as photosynthesis and transpiration rates of wellwatered potato plants. However, only soil application increased P concentration in leaves and dry weight of leaves and stems. © Crop Science Society of America.

Qualidade tecnológica e produtividade agroindustrial de cana-deaçúcar submetida a adubação com zinco

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Occurrence of Cu and Cr in the sedimentary humic substances and pore water from a typical sugar cane cultivation area in São Paulo, Brazil

Purpose: The purpose of this paper is to study the interactions of sedimentary humic substances (SHS) from a sugarcane cultivation area with Cu(II) and Cr(III) and to evaluate the occurrence of these metals in the pore water and SHS. Materials and methods: For this study, the northwestern region of the State of São Paulo, Brazil, which is considered the region with the highest production of sugar cane in the state, was selected. Samples of sediment were collected from four sampling sites in the Preto, Turvo, and Grande rivers. The SHS and pore water were extracted from the sediment using the method suggested by the International Humic Substances Society and centrifugation, respectively. The complexing capacity (CC) of the SHS for Cu(II) and Cr(III) was determined by individually titrating these metals with an ultrafiltration system using tangential flow. The total concentrations of Cr and Cu were determined for the pore water, sediments, and humic substances with graphite furnace atomic absorption spectrometry and Zeeman background correction after an acid digestion, according to the methods described in US EPA Method 3050B. Results and discussion: The SHS from a site in the Turvo River, which is typically cultivated with sugarcane, possessed the highest concentration of Cu bound to SHS (25.0%), the largest CC (0.63 mmol Cu g-1 HS) and the highest concentration of this metal in the pore water (1.38 mg Cu Kg-1 sed.). For Cr, the SHS collected from a location on the Preto River dam had the largest CC (0.90 mmol Cr g-1 HS) and the lowest Cr content in the pore water (0.29 mg Cr Kg-1 sed.), indicating that there was an inverse relationship between the CC and the concentration of metal available in the pore water. Conclusions: Sedimentary humic substances might be one of the regulatory factors controlling the availability of Cu and Cr in the sediments found in a typical region that has been planted with sugarcane. Distinct behaviors were observed between the two elements investigated; higher CC and a larger fraction of Cu(II) were found in the pore water of samples originating from sugarcane crops. The opposite behavior was observed for the Cr(III) species. © 2013 Springer-Verlag Berlin Heidelberg.

La reforma laboral en la encrucijada

Incluye Bibliografía

La migración rural en México y sus posibles efectos en la población y economía campesina: el caso de Ayapango, Estado de México; trabajo final

Incluye Bibliografía

Características de la población migrante del distrito de San Miguelito; Provincia de Panamá

Incluye Bibliografía

Paternidad responsable en el Istmo Centroamericano

Incluye Bibliografía

Reação de 16 porta-enxertos sob laranjeira 'Valência' ao agente causal, Candidatus Liberibacter asiaticus

Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

Gestión urbana en ciudades intermedias de América Latina: consideraciones sobre el marco conceptual

Incluye Bibliografía

Regímenes competitivos sectoriales, productividad y competitividad internacional

Resumen A partir de estadísticas de producción y empleo, por una parte, y de competitividad "revelada" internacional, por otra, el estudio examina el impacto que sobre distintos países de América Latina y el Caribe han tenido las reformas pro-competitivas de años recientes. Se muestra cómo se han ido perfilando en la región dos grandes "modelos dominantes": el de las industrias procesadoras de recursos naturales, en los países del Cono Sur de la región, y el de la "maquila" -electrónica y del vestuario- en México y varios países más pequeños de América Central. El trabajo muestra, además, cómo dicho proceso de cambio en el patrón de especialización productiva y competitividad internacional ha estado asociado a fenómenos de entrada y salida de firmas de y a los mercados, de absorción y expulsión ocupacional, de cambios en las "fuentes" de progreso tecnológico y, finalmente, de sustentabilidad de las cuentas externas de cada economía. El trabajo concluye con una breve discusión sobre políticas posibles de desarrollo productivo y competencia destinadas a mejorar la productividad y competitividad internacional de las economías de la región.

Políticas públicas y migración interna en la República Bolivariana de Venezuela contemporánea

Las transformaciones del aparato productivo, los cambios en la economía global y ciertos factores políticos y sociales han configurado diversos patrones de movilidad territorial. El interés de esta investigación se centra en analizar las tendencias de la migración interna en la República Bolivariana de Venezuela desde 1971 hasta 2001. Sobre la base de la información suministrada por los censos de población y vivienda se elaboraron matrices de origen y destino multirregionales que permitieron identificar la direccionalidad de los flujos y establecer áreas tradicionales y emergentes de atracción y expulsión. La regionalización, construida a partir del índice de desarrollo humano, permitió distinguir corrientes migratorias entre regiones de alto, medio y bajo desarrollo humano, que evidencian la desigual distribución de las actividades productivas dentro del territorio nacional. Finalmente, el análisis de los resultados en el marco de los procesos histórico-estructurales demostró el vínculo que existe entre las decisiones políticas, la activación económica de los territorios y la dinámica migratoria interna.

Ilha Solteira e Projeto Cinturão Verde: história e contradições

Pós-graduação em Serviço Social - FCHS

Metabolômica, uma abordagem otimizada para exploração da biodiversidade brasileira: estado da arte, perspectivas e desafios

Brazilian biodiversity is a colossal source of secondary metabolites with remarkable structural features, which are valuable in further biodiscovery studies. In order to fully understand the relations and interactions of a living system with its surroundings, efforts in natural product chemistry are directed toward the challenge of detecting and identifying all the molecular components present in complex samples. It is plausible that this endeavor was born out of recent technological sophistication in secondary metabolite identification with sensitive spectroscopic instruments (MS and NMR) and higher resolving power of chromatographic systems, which allow a decrease in the amount of required sample and time to acquire data. Nevertheless, the escalation of data acquired in these analyses must be sorted with statistical and multi-way tools in order to select key information. Chromatography is also of paramount importance, more so when selected compounds need to be isolated for further investigation. However, in the course of pursuing a greener environment, new policies, with an aim to decrease the use of energy and solvents, are being developed and incorporated into analytical methods. Metabolomics could be an effective tool to answer questions on how living organisms in our huge biodiversity work and interact with their surroundings while also being strategic to the development of high value bio-derived products, such as phytotherapeutics and nutraceuticals. The incorporation of proper phytotherapeutics in the so-called Brazilian Unified Health System is considered an important factor for the urgent improvement and expansion of the Brazilian national health system. Furthermore, this approach could have a positive impact on the international interest toward scientific research developed in Brazil as well as the development of high value bio-derived products, which appear as an interesting economic opportunity in national and global markets. Thus, this study attempts to highlight the recent advances in analytical tools used in detection of secondary metabolites, which can be useful as bioproducts. It also emphasizes the potential avenues to be explored in Brazilian biodiversity, known for its rich chemical diversity.

Caracterização dos aspectos vocais de um coro infantojuvenil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Wickerhamiella kiyanii f.a., sp nov and Wickerhamiella fructicola f.a., sp nov., two yeasts isolated from native plants of Atlantic rainforest in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)