Mostrando recursos 1 - 20 de 1.569

  1. Alleviation of salt stress using exogenous proline on a citrus cell line

    Lima-Costa, M. E.; Ferreira, S.; Duarte, Amilcar; Ferreira, A. L.
    Salinity constitutes an important abiotic problem since ancient times, world-wide, for it leads to a decrease in productivity of crops with agronomic value. Under salt stress conditions, plant cells develop strategies to cope with Na+ and Cl-, including exclusion and compartmentalisation, induction of antioxidant enzymatic systems and compatible solutes accumulation, such as proline. The precise function of this osmolyte still remains unclear. Proline may act on osmotic adjustment, as a free radical scavenger, protecting enzymes and avoiding DNA damages. It has been also suggested the role of proline in prevention of lipid peroxidation and as a signalling/regulatory molecule. A salt-sensitive...

  2. Production of carotenoids by microalgae: achievements and challenges

    Varela, J.; Pereira, Hugo; Vila, Marta; León, Rosa
    Carotenoids are a wide group of lipophylic isoprenoids synthesized by all photosynthetic organisms and also by some non-photosynthetic bacteria and fungi. Animals, which cannot synthesize carotenoids de novo, must include them in their diet to fulfil essential provitamin, antioxidant, or colouring requirements. Carotenoids are indispensable in light harvesting and energy transfer during photosynthesis and in the protection of the photosynthetic apparatus against photooxidative damage. In this review, we outline the factors inducing carotenoid accumulation in microalgae, the knowledge acquired on the metabolic pathways responsible for their biosynthesis, and the recent achievements in the genetic engineering of this pathway. Despite the considerable progress achieved in understanding and engineering algal carotenogenesis, many aspects remain to...

  3. Uso de desbrozadora como alternativa a los herbicidas en el control de malas hierbas, en naranjo ‘Rhode’

    Duarte, Amílcar; Martins, A.
    La lucha contra malas hierbas en cítricos constituye un problema por el coste de las operaciones, el gasto de energía y el impacto ambiental cuando se usan herbicidas. Por estas razones, es importante estudiar y divulgar métodos alternativos al uso de los herbicidas. El presente estudio demuestra que en el cultivo del naranjo ‘Rhode’, el uso de una desbrozadora es igualmente eficaz que el uso de un herbicida. Los resultados demuestran que la cosecha y el calibre del fruto no son afectados por el cambio de método de control de malas hierbas. Además, se facilita la movilidad de maquinaria dentro del...

  4. El rajado estilar del fruto en los citricos: aspectos anatomicos y morfologicos

    García-Luis, A.; Kanduser, M.; Duarte, Amílcar; Guardiola, J. L.
    El rajado o agrietado es una alteración del fruto, y aun de otras partes utilizables de la planta, que se caracteriza por la formación de fisuras profundas en la piel o corteza de tal modo que la parte interna comestible del fruto queda expuesta y aun se agrieta. El fruto afectado en muchos casos se desprende prematuramente, pero aun en el caso de que complete su desarrollo y alcance la maduración es inservible para la comercialización. Esta alteración se ha descrito en gran número de especies, entre las que se encuentran frutales de hueso y de pepita, plantas hortícolas (como el...

  5. Acidentes fisiológicos do fruto em tangerineira “encore”

    Pinto, M. J.; Duarte, Amílcar
    A tangerineira “Encore”é uma variedade muito popular em Portugal, mas que apresenta alguns problemas de cultivo, nomeadamente por ter uma marcada tendência para alternância de produção e por apresentar algum rachamento dos frutos. Além disso, os seus frutos apresentam manchas caracteristicas que desvalorizam a produção.

  6. Aplicação de retardadores de crescimento em citrinos ornamentais

    Pinto, M. J.; Faustino, J .J.; Duarte, Amílcar
    Tendo por objectivo a avaliação dos efeitos de alguns retardadores de crescimento no desenvolvimento vegetativo de citrinos ornamentais, para posterior utilização pelos viveiristas, foi estudado o efeito da aplicação, por pulverização, de quatro retardadores de crescimento a diferentes concentrações, sobre duas espécies do género Fortunella sp. ( F. margarita [ Lour. ] Swing. e F. Obovata Tan. ). Estudámos o efeito da daminozida a 5600, 7500 e 9400 ppm; paclobutrazol a 180, 240 e 300 ppm; CCC a 1050, 1400 e 1750 ppm e dikegulac a 3000, 4000 e 5000 ppm. O desenvolvimento vegetativo das plantas foi observado ao longo de...

  7. Structure and Genetic Variability of the Oceanic Whitetip Shark, Carcharhinus longimanus, Determined Using Mitochondrial DNA

    Camargo, Samia M.; Coelho, Rui; Chapman, Demian; Howey-Jordan, Lucy; Brooks, Edward J.; Fernando, Daniel; Mendes, Natalia J.; Hazin, Fabio H. V.; Oliveira, Claudio; Santos, Miguel N.; Foresti, Fausto; Mendonca, Fernando F.
    Information regarding population structure and genetic connectivity is an important contribution when establishing conservation strategies to manage threatened species. The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, large-bodied, pelagic shark listed by the IUCN (International Union for Conservation of Nature) Red List as "vulnerable" throughout its range and "critically endangered" in the western north Atlantic. In 2014, the species was protected globally under Appendix II of CITES (Convention on International Trade in Endangered Species), limiting and regulating trade. This study used partial sequences of mitochondrial DNA (mtDNA) control region to determine the population genetic structure of oceanic whitetip...

  8. Microsatellite loci in the tiger shark and cross-species amplification using pyrosequencing technology

    Mendes, Natalia J.; Cruz, Vanessa P.; Ashikaga, Fernando Y.; Camargo, Samia M.; Oliveira, Claudio; Piercy, Andrew N.; Burgess, George H.; Coelho, Rui; Santos, Miguel N.; Mendonca, Fernando F.; Foresti, Fausto
    The tiger shark (Galeocerdo cuvier) has a global distribution in tropical and warm temperate seas, and it is caught in numerous fisheries worldwide, mainly as bycatch. It is currently assessed as near threatened by the International Union for Conservation of Nature (IUCN) Red List. In this study, we identified nine microsatellite loci through next generation sequencing (454 pyrosequencing) using 29 samples from the western Atlantic. The genetic diversity of these loci were assessed and revealed a total of 48 alleles ranging from 3 to 7 alleles per locus (average of 5.3 alleles). Cross-species amplification was successful at most loci for...

  9. Thinning of ‘Esbal’ clementine with 2,4-dichlorophenoxyacetic acid. Influence on yield, fruit size and fruit quality.

    Duarte, Amílcar; Trindade, D. T. G.; Guardiola, J. L.
    Esbal clementine, which originated as a bud sport from ‘Fina’, is a high parthenocarpyc early maturing cultivar with outstanding fruit quality. The expansion of this cultivar is nevertheless impaired by the small fruit size, as up to 40% of the total yield may be unmarketable due to this reason. Extensive hand thinning and auxin applications at June drop have been tried to overcome this problem with limited success. The application of a 2,4-D spray at or shortly after bloom thins effectively the number of fruits without affecting total yield, reducing the percentage of unmarketable fruit down to 13% and increasing...

  10. Coastal storm risk assessment in Europe: examples from 9 study sites

    Ferreira, Óscar; Ciavola, P.; Armaroli, C.; Balouin, Y.; Benavente, J.; Del Río, L.; Deserti, M.; Esteves, L. S.; Furmanczyk, K.; Haerens, P.; Matias, A.; Perini, L.; Taborda, R.; Terefenko, P.; Trifo, E.
    To assess coastal storm risks thi paper compares existing hazards, associated risks, coastal management plans, and civil protection schemes from nine European countries.

  11. Aplicaciones del calcio en citricultura

    Duarte, Amílcar; Guardiola, J. L.
    La esencialidad del calcio para las plantas se estableció de modo inequívoco hace más de cien años, incluyéndose ya como componente en las primeras soluciones nutritivas que se desarrollaron.Lav presencia de calcio en la solución nutritiva se demotró necesaria para el crecimiento de la raíz, que en su ausencia se detiene en el plazo de unas poucas horas.

  12. Equation of state of a laser-cooled gas

    Rodrigues, J. D.; Rodrigues, J. A.; Moreira, O. L.; Tercas, H.; Mendonca, J. T.
    We experimentally determine the equation of state of a laser-cooled gas. By employing the Lane-Emden formalism, widely used in astrophysics, we derive the equilibrium atomic profiles in large magneto-optical traps where the thermodynamic effects are cast in a polytropic equation of state. The effects of multiple scattering of light are included, which results in a generalized Lane-Emden equation for the atomic profiles. A detailed experimental investigation reveals an excellent agreement with the model, with a twofold significance. On one hand, we can infer the details of the equation of state of the system, from an ideal gas to a correlated...

  13. Bougainvillea post-production: NAA and STS control of bract abscission is subject to exogenous ethylene

    Gago, C. M. L.; Monteiro, José A.; Rodrigues, M. H.
    The effect of NAA (500 mg.L-1 sprayed once at end-of-production), STS (0.4 mM sprayed every 15 days after bracts started to be apparent) and STS+NAA on plants exposed or not to exogenous ethylene (from ethephon), were tested using two completely randomized experiments. At the end-of-production plants were placed for three days under simulated transport conditions (17 +/-1 degreesC, no light) and then, placed under interior conditions (21 +/-1 degreesC and 11 mu mol.m(-2)s(-1) of cool white fluorescent light 12 hr a day). Twice a week, during postproduction (PP) the number of developing (D) bracts as well as the number of...

  14. Beach erosion and recovery during consecutive storms at a steep-sloping, meso-tidal beach

    Vousdoukas, Michalis I.; Almeida, Luis Pedro M.; Ferreira, Óscar
    This study analyses beach morphological change during six consecutive storms acting on the meso-tidal Faro Beach (south Portugal) between 15 December 2009 and 7 January 2010. Morphological change of the sub-aerial beach profile was monitored through frequent topographic surveys across 11 transects. Measurements of the surf/swash zone dimensions, nearshore bar dynamics, and wave run-up were extracted from time averaged and timestack coastal images, and wave and tidal data were obtained from offshore stations. All the information combined suggests that during consecutive storm events, the antecedent morphological state can initially be the dominant controlling factor of beach response; while the hydrodynamic forcing, and especially the tide and...

  15. Os compostos no controlo de doenças das plantas

    Reis, Mário
    A compostagem permite obter produtos, designados compostados ou compostos, que em alguns casos, apresentam a capacidade de reduzir ou eliminar doenças das plantas com origem no solo - capacidade supressiva ou supressividade - o que lhes confere um interesse acrescido ao de fertilizantes agrícolas, objectivo com que habitualmente se empregam. Neste trabalho, após breve descrição da compostagem, são referidos os mecanismos de supressividade, as condições para a obtenção de compostos supressivos, os métodos de quantificação da supressividade e referem-se alguns exemplos de compostos com capacidade supressiva. O conhecimento sobre a capacidade supressiva dos compostos é uma área de estudo com...

  16. Combined expression of p20 and p23 proteins from Citrus tristeza virus show enhanced local silencing suppressor activity

    Costa, Angela A.; Martins, Tatiana R.; Marques, Natalia T.; Nolasco, Gustavo
    Viruses developed a strategy to counter-defence the posttranscriptional gene silencing mechanism (PTGS) based on the activity of silencing suppressor proteins. Citrus tristeza virus (CTV), a member of the genus Closterovirus, has two suppressor proteins (p20 and p23) that target the local RNA silencing response of the host. In GFP transient co-expression assays performed on Nicotiana benthamiana 16C plants, local suppressor activity of p23 and p20 was similar. Co-expression of both proteins from a mild or a stem pitting CTV isolate showed stronger local suppression activity than either suppressor alone, with an increased GFP transcript level six-(for Gp M) to nine-fold...

  17. RISC-KIT: Resilience-increasing Strategies for Coasts

    Van Dongeren, Ap; Ciavola, Paolo; Martinez, Grit; Viavattene, Christophe; DeKleermaeker, Simone; Ferreira, Óscar; Costa, Cristina; McCall, Robert
    High-impact storm events have demonstrated the vulnerability of coastal zones in Europe and beyond. These impacts are likely to increase due to predicted climate change and ongoing coastal development. In order to reduce impacts, disaster risk reduction (DRR) measures need to be taken, which prevent or mitigate the effects of storm events. To drive the DRR agenda, the UNISDR formulated the Sendai Framework for Action, and the EU has issued the Floods Directive. However, neither is specific about the methods to be used to develop actionable DRR measures in the coastal zone. Therefore, there is a need to develop methods,...

  18. CRAF Phase 1, a framework to identify coastal hotspots to storm impacts

    Ferreira, Óscar; Viavattene, Christophe; Jimenez, Jose; Bole, Annelies; Plomaritis, Theocharis; Costas, Susana; Smets, Steven
    Low-frequency high-impact storms can cause flood and erosion over large coastal areas, which in turn can lead to a significant risk to coastal occupation, producing devastation and immobilising cities and even countries. It is therefore paramount to evaluate risk along the coast at a regional scale through the identification of storm impact hotspots. The Coastal Risk Assessment Framework Phase 1 (CRAF1) is a screening process based on a coastal-index approach that assesses the potential exposure of every kilometre along the coast to previously identified hazards. CRAF1 integrates both hazard (e.g. overwash, erosion) and exposure indicators to create a final Coastal...

  19. Predicting coastal hazards for sandy coasts with a Bayesian Network

    Poelhekke, Laurens; Jager, Wiebke S.; Van Dongeren, Ap; Plomaritis, Theocharis A.; McCall, Robert; Ferreira, Óscar
    Low frequency, high impact storm events can have large impacts on sandy coasts. The physical processes governing these impacts are complex because of the feedback between the hydrodynamics of surges and waves, sediment transport and morphological change. Predicting these coastal changes using a numerical model requires a large amount of computational time, which in the case of an operational prediction for the purpose of Early Warning is not available. For this reason morphodynamic predictions are not commonly included in Early Warning Systems (EWSs). However, omitting these physical processes in an EWS may lead to potential under or over estimation of...

  20. Determination of thresholds for storm impacts

    Ferreira, Óscar; Almeida, L. P.; Rodrigues, B.; Matias, A.
    Storms are responsible for important erosion, coastal retreat and damage when infrastructures are placed within their acting area. The characterisation of storm parameters and associated thresholds for erosion and damage are therefore of fundamental importance for coastal management purposes. This work presents ways of determining thresholds for important morphological changes (including erosion), overwash occurrence and damage associate to storm occurrence. These methods were tested and applied to Ancão Peninsula (South Portugal) and the results shown. The use of these approaches will enable coastal managers to have a quantitative knowledge of consequences associated to each particular storm and to act accordingly, for instance defining set-back lines, designing nourishments or implementing evacuation...

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