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)

Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit Tocantins Fossil Trees Natural Monument In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures. © 2013 Elsevier Ltd.

Genetic variability for temperament indicators of Nellore cattle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Association between indicators of dementia and nutritional status in institutionalised older people

Background and aims. Dementia weakens older people and can lead to malnutrition; therefore, the objective of this study was to assess the association between indicators of dementia and biochemical indicators, anthropometric indicators and food intake in institutionalised older people. Methods. A total of 150 older people of both genders participated in this study. Nutritional status was determined by body mass index and other anthropometric variables, and biochemical indicators were used to analyse the differences between individuals with and without dementia. Energy and nutrient intakes were determined by food records, and dementia was investigated with the Mini-Mental State Examination. The data were analysed by the chi-square test, Student's t-test and Mann-Whitney tests. Results. Of the 150 individuals studied, 48% were men with a mean age of 73±10years and 52% were women with a mean age of 80±9years. Thirty-six per cent had some degree of malnutrition and 48% presented dementia, which was more prevalent in women (59%). The nutritional status of men and women individuals with and without dementia differed significantly (P<0.001 for men and women). The only variables that presented a significant difference between individuals with and without dementia were those associated with muscle mass in men. There were no differences in energy and nutrient intakes between individuals with and without dementia except for vitamin C intake, which differed among women (P=0.032). Conclusion. In the conditions of the present study, dementia was associated with nutritional status, but not with energy and nutrient intakes, suggesting that older people with dementia may have higher nutritional requirements. Implications for practice. Investigation of dementia may contribute to the nutritional status assessment of older people and energy expenditure and immobility should be investigated for a more complete assessment. © 2012 Blackwell Publishing Ltd.

Current status, uncertainty and future needs in soil organic carbon monitoring

Increasing human demands on soil-derived ecosystem services requires reliable data on global soil resources for sustainable development. The soil organic carbon (SOC) pool is a key indicator of soil quality as it affects essential biological, chemical and physical soil functions such as nutrient cycling, pesticide and water retention, and soil structure maintenance. However, information on the SOC pool, and its temporal and spatial dynamics is unbalanced. Even in well-studied regions with a pronounced interest in environmental issues information on soil carbon (C) is inconsistent. Several activities for the compilation of global soil C data are under way. However, different approaches for soil sampling and chemical analyses make even regional comparisons highly uncertain. Often, the procedures used so far have not allowed the reliable estimation of the total SOC pool, partly because the available knowledge is focused on not clearly defined upper soil horizons and the contribution of subsoil to SOC stocks has been less considered. Even more difficult is quantifying SOC pool changes over time. SOC consists of variable amounts of labile and recalcitrant molecules of plant, and microbial and animal origin that are often operationally defined. A comprehensively active soil expert community needs to agree on protocols of soil surveying and lab procedures towards reliable SOC pool estimates. Already established long-term ecological research sites, where SOC changes are quantified and the underlying mechanisms are investigated, are potentially the backbones for regional, national, and international SOC monitoring programs. © 2013 Elsevier B.V.

Economic indicators of Latin America and the Caribbean, 2003

Includes bibliography

Some macro indicators of the Caribbean countries: 1950-1970 selected years

Includes bibliography

Selected statistical indicators of Caribbean countries

Includes bibliography

Selected statistical indicators of Caribbean countries: vol. II

Includes bibliography

Selected statistical indicators of Caribbean countries: vol. III

Includes bibliography