Chromosome doubling in Tripsacum : the production of artificial, sexual tetraploid plants

Une collection de cals diploïdes et embryogènes de #Tripsacum$ a été constituée et traitée à la colchicine pour induire des doublements chromosomiques. Des sections de cals présentant des cellules dupliquées ont été identifiées par cytométrie en flux, et le niveau de ploïdie des plantules régénérées à partir de ces sections déterminé. Des plantes tétraploïdes, d'origines différentes, ont ainsi été obtenues. Contrairement aux plantes polyploïdes sauvages qui se reproduisent apomictiquement, les plantes tétraploïdes régénérées ont un mode de reproduction sexué. Différentes populations, issues du croisement de ces plantes avec des génotypes tétraploïdes et apomictiques, ont été produites: celles-ci permettront l'étude du contrôle génétique de l'apomixie. (Résumé d'auteur

Probabilistic and predictive performance-based approach for assessing reinforced concrete structures lifetime: The applet project

International audienceConcrete deterioration results in different damage extents, from cracking to concrete spalling, from losses of reinforcement cross-sections to bond losses. A relevant prediction of this performance is the basis for a successful management of the concrete structures. Conversely, the large amount of uncertainties related to parameters and models require a specific analysis in order to provide relevant results. The APPLET project intends to develop a probabilistic and predictive performance-based approach by quantifying the various sources of variability (material and structure), studying the interaction between environmental aggressive agents and the concrete material, ensuring a transfer of the physical-chemical models at the material scale towards models at the structure level, including and understanding in a better manner the corrosion process, integrating interface models between reinforcement and concrete, proposing relevant numerical models, integrating know-how from monitoring or inspection. To provide answers, a consortium of 19 partners has been established and has promoted a research project funded by the French Research Science Agency (ANR). Started in May 2007, the project has ended in November 2010. This paper will resume the most significant advances targeted by this research project

Sequencing and Welding of Molecular Single-Crystal Optical Waveguides

Molecular crystals are promising anisotropic optical transducing media for next-generation optoelectronic microdevices that will be capable of secure transduction of information and impervious to external electromagnetic interference. However, their full potential has not been explored yet due to their poor processability, low mechanical compliance, pronounced brittleness and high proneness to cracking that often result in irrecoverable damage. These issues are detrimental to their ability to transduce light. Here, a novel strategy is presented based on 3D epitaxial crystal growth of organic/inorganic crystals based on charge-assisted hydrogen bonds that can be used to efficiently weld broken molecular single-crystalline optical waveguides and restore their light-transducing capability. This approach can also be applied to prepare asymmetric multidomain crystalline heterostructures starting from isostructural molecular tectons, resulting in novel opto/electro/mechanical functionalities in the hybrid materials. It also removes an important obstacle toward wider application of molecular crystals in the next-generation optoelectronics

Resposta do dendezeiro à aplicação de fertilizantes nas condições do Estado do Amazonas.

O presente trabalho visa estudar o efeito da adubação nitrogenada, fosfatada, potássica e magnesiana no desenvolvimento e na produção do dendezeiro.bitstream/item/89200/1/PA-08-Maria-do-Rosario.pd

Dendê uma opção de cultivo para áreas degradadas na Amazônia.

O cultivo de dende surge como opcao para exploracao na Amazonia, tendo em vista sua adaptacao as condicoes edafoclimaticas da regiao. Esta cultura, com vida util de 25 anos, inicia sua producao aos quatro anos, tem produtividade media de 4t/oleo/ha/ano - 6t/oleo/ha/ano, colheita durante o ano todo, ausencia de entressafra, demanda expressivo contigente de mao-de-obra, fixando, dessa maneira, o homem na zona rural. Buscando apoiar e incentivar a expansao da cultura, a EMBRAPA-CPAA e o IRHO implantaram, no Amazonas, varios ensaios, objetivando desenvolver um programa de melhoramento, para a obtencao de material mais produtivo e melhor adaptado as condicoes da regiao. A producao media experimental de cachos aos quatro anos de idade variou de 12t/ha. Atualmente, EMBRAPA/CIRAD produzem sementes comerciais para atender os dendeicultores da regiao

Bedrock erosion by root fracture and tree throw: A coupled biogeomorphic model to explore the humped soil production function and the persistence of hillslope soils

In 1877, G. K. Gilbert reasoned that bedrock erosion is maximized under an intermediate soil thickness and declines as soils become thinner or thicker. Subsequent analyses of this “humped” functional relationship proposed that thin soils are unstable and that perturbations in soil thickness would lead to runaway thinning or thickening of the soil. To explore this issue, we developed a numerical model that simulates the physical weathering of bedrock by root fracture and tree throw. The coupled biogeomorphic model combines data on conifer population dynamics, rootwad volumes, tree throw frequency, and soil creep from the Pacific Northwest (USA). Although not hardwired into the model, a humped relationship emerges between bedrock erosion and soil thickness. The magnitudes of the predicted bedrock erosion rates and their functional dependency on soil thickness are consistent with independent field measurements from a coniferous landscape in the region. Imposed perturbations of soil erosion during model runs demonstrate that where bedrock weathering is episodic and localized, hillslope soils do not exhibit runaway thinning or thickening. The pit-and-mound topography created by tree throw produces an uneven distribution of soil thicknesses across a hillslope; thus, although episodes of increased erosion can lead to temporary soil thinning and even the exposure of bedrock patches, local areas of thick soils remain. These soil patches provide habitat for trees and serve as nucleation points for renewed bedrock erosion and soil production. Model results also suggest that where tree throw is a dominant weathering process, the initial mantling of bedrock is not only a vertical process but also a lateral process: soil mounds created by tree throw flatten over time, spreading soil over bedrock surfaces

Ocorrência de um surto de anel vermelho do dendê no Estado do Amazonas.

A cultura do dendê no Brasil é afetada por importantes doenças, com destaque para anel-vermelho (Rhadinaphelenchus cocophilus). No estado do Amazonas, os plantios de dendê são recentes, e, normalmente, estabelecidos em áreas próximas de floresta. A intensificação das práticas de poda e colheita, por ocasião do início da produção, tende a expor as plantas ao ataque do inseto vetor Rhynchophorus palmarum. Na estação experimental do CPAA, onde existe um banco de germoplasma de dendê plantado em 412ha, foi constatado recentemente um surto dessa doença. Estudos estão sendo conduzidos visando determinar a população anual do inseto vetor e os níveis de contaminação deste com os nematóides.Edição dos resumos do XXVIII Congresso Brasileiro de Fitopatologia. Resumo 421