22,354 research outputs found

    Generating and evaluating a novel genetic resource in wheat in diverse environments

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    The principal objective of the project is to develop composite cross populations of wheat based on a wide range of key parent varieties. The parents will be selected partly on past knowledge of successful performance in terms of yield, quality and disease resistance and partly on the basis of molecular ancestry to try to ensure as wide range of diversity as possible. Following parental inter-crossing in all possible combinations, progeny population samples will be exposed to a range of widely different agricultural environments and systems through several seasons of, largely, natural selection. Performance of the population samples will be compared at different stages against both the parents grown as pure stands and as physical mixtures. Our objective is to increase the sustainability and competitiveness of organic and other extensive farming systems by developing genetically diverse wheat populations that will respond rapidly to on-farm selection for improved productivity and yield. It is well established that modern varieties of wheat perform poorly under the conditions and management options encountered in organic farming systems. This is due to a number of factors including poor competition against weeds, narrow resistance against pests and disease, inability to efficiently utilise soil bound nutrients and the lack of genetic flexibility to buffer against environmental variation. To develop a conventional, new wheat breeding programme, from start to release of adapted varieties, would take many years. The approach we propose can deliver this material quickly. This will be achieved through the production of appropriate composite-cross populations of winter wheat. The research will provide material adapted to basic organic conditions that can then be further selected on-farm. This will also be of benefit to non-organic farms as the populations will posses broad resistance to pests and disease and improved competitive ability against weeds, so minimising the need for crop protection inputs. The research will deliver a unique insight into the evolution of genetically diverse wheat populations, under a diverse range of environments, which will allow the elucidation of gene x environment interactions. In addition, it will provide information on the characters of winter wheat that confer improved productivity under a diversity of environmental conditions. Samples of the resulting winter wheat composite cross populations will be placed in the gene bank at the John Innes Centre. Overall objective: To increase the sustainability and competitiveness of both non-organic and organic farming systems by developing genetically diverse wheat populations that will respond rapidly to on-farm selection for improved productivity and yield. 1. To generate six distinct, highly heterogeneous composite-cross populations of winter wheat for further development and selection. The populations will comprise; one with parental material selected for good milling potential, one with parents selected for high yield potential and one comprising both sets of parent material. Each of these populations will then be split to either include or exclude heritable male sterility. 2. To evaluate the performance and evolution of composite-cross populations over time under a diverse range of environmental conditions and identify characteristics that confer improved productivity in these environments. 3. To track the genetic changes that accompany selection, so providing a better understanding of the assemblages of traits that underlie improved productivity in diverse environments. 4. To provide genetically diverse crop material for further selection by farmers and as a resource for future publicly funded research. 5. To disseminate the results to the scientific community and industr

    Pioneer 10 Jupiter atmospheric definition results: A summary

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    The various entry probes for measuring outer planetary atmospheric compositions are discussed. Considered are chemical components and physical accumulation processes observable by spectroscopic studies, as well as pressure gauges, temperature gauges, accelerometers, nephelometers, and visible and infrared sensors for determining abundances

    "Rewiring" Filterbanks for Local Fourier Analysis: Theory and Practice

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    This article describes a series of new results outlining equivalences between certain "rewirings" of filterbank system block diagrams, and the corresponding actions of convolution, modulation, and downsampling operators. This gives rise to a general framework of reverse-order and convolution subband structures in filterbank transforms, which we show to be well suited to the analysis of filterbank coefficients arising from subsampled or multiplexed signals. These results thus provide a means to understand time-localized aliasing and modulation properties of such signals and their subband representations--notions that are notably absent from the global viewpoint afforded by Fourier analysis. The utility of filterbank rewirings is demonstrated by the closed-form analysis of signals subject to degradations such as missing data, spatially or temporally multiplexed data acquisition, or signal-dependent noise, such as are often encountered in practical signal processing applications
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