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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

The evaluation of 391 spring wheat introductions for resistance to stem and leaf rust, loose smut and tan spot

Claude, Pierre-Philippe 03 October 2012 (has links)
Three hundred ninety one (391) spring wheat introductions from Asian, Middle Eastern and Mediteranean areas were screened for resistance to races C17, C20, C25, C49, C53 and C57 of Puccinia qraminis tritici; races 1, 5, 9, 15 and bulks 1, 4 and l0 of Puccinia recondita; races T2, T10, T13 and T39 of Ustilago tritici and to 6 isolates of Drechslera tritici-repentis prevalent in western Canada. Of the 34 introductions resistant to P. graminis tritici, 15 were genetically studied using F2 segregation data derived from the progeny of the crosses involving resistant introductions, their corresponding near isogenic lines and stem rust universal suscepts. Eleven of these were found to carry single Sr genes for resistance, notably, Sr30, Sr13 and Sr15. Of the 70 introductions resistant to P. recondita, 28 were studied and 9 were found to carry known Lr genes for resistance, notably Lr10 and the genes present in RL6057 and RL6061. Twenty two introductions are believed to carry either 1 or 2 unidentified dominant, recessive, partially dominant and/or complementary genes for resistance to either stem or leaf rust. Five introductions were immune and 6 highly resistant to the 4 races of U. tritici. Sixty-nine introductions were resistant to D. tritici-repentis . These were arbitrarily classified into 10 'phenotypic classes' according to their reactions to the 6 isolates used.
222

The genetics of leaf rust resistance in the durably resistant wheat cultivar ‘Toropi’

Barcellos Rosa, Silvia 04 January 2013 (has links)
Wheat is infected by leaf rust disease (Puccinia triticina Eriks.) almost everywhere it is cultivated. The dynamic nature of P. triticina populations affects the effective life span of genes conferring leaf rust resistance (Lr genes). Genetic diversity and combinations of Lr genes should be used to achieve durable resistance. Toropi, a Brazilian wheat cultivar, has maintained leaf rust resistance since its release in 1965, suggesting that it is a good candidate for durable resistance. Two recessive complementary adult plant genes were previously described in Toropi. The objective of this study was to characterize and map the sources of resistance present in Toropi. Double haploid (DH) populations developed by crossing the susceptible leaf rust cultivar Thatcher with Toropi were analysed in Canada (Glenlea – 2010 and Portage La Prairie – 2011), New Zealand (Lincoln – 2010 and 2011) and in Brazil (Parana – 2011), and in greenhouse. The leaf rust reactions indicated the presence of at least four leaf rust resistance genes in Toropi: one seedling gene and three adult plant genes. The seedling resistance gene Trp-Se, responsible for immune response in New Zealand, was mapped on chromosome 3D. QTL analyses identified a QTL associated with leaf rust resistance (QLr.crc-5AL.1) on chromosome 5AL, which overlapped with a QTL for stripe rust (QStr.crc-5AL.1) in the same population. This gene, designated Trp1, is believed to be one of the two adult plant complementary partial resistance genes. The position of the Trp-2 is not confirmed yet. One minor race specific adult plant gene, temporarily designated Trp-3, was mapped on 4BL chromosome. The Lr genes in Toropi confer minor effects against leaf rust, except for Trp-Se, which conditioned immunity in New Zealand. However, when the Toropi Lr genes were combined an almost immune response resulted. Toropi had a very good leaf rust resistance in South and North America, and in New Zealand. The molecular markers identified during this project could facilitate the incorporation of the Toropi genes in new cultivars, helping to achieve more diverse and durable wheat.
223

The Foraging Areas of Attine Ants at the Firestone Reserve, Costa Rica

Goldstein, Elana A 01 January 2014 (has links)
In tropical forest systems, attine ants are the dominant herbivores. They construct large nest structures that include foraging trails that extend to multiple plant sources throughout the forest. These foraging areas vary from nest to nest and they are highly dynamic over time and season changes. It was expected that characteristics of both the nest structure and the surrounding environment would affect the size of nest foraging areas. In this study, COMPASS survey software and ArcGIS were used to map the foraging trails and calculate the foraging areas of 12 attine ant nests located on the Firestone Reserve, over the course of 6 weeks. Data collected at the ant nest sites on nest area, flow rate, trail number and neighboring nest proximity were combined with data collected from previous studies on soil pH and light fractions in order to test correlation hypotheses between these factors and foraging area. The mean foraging areas differed significantly from each other and significant correlations were found between foraging area and trail number, flow rate, neighbor distance and soil pH. Understanding foraging behavior of attine ants is important in the field of restoration ecology because these ants are important in determining overall structure and nutrient distribution in tropical forests.
224

Plant species biometric using feature hierarchies

Pahalawatta, Kapila January 2008 (has links)
Biometric identification is a pattern recognition based classification system that recognizes an individual by determining its authenticity using a specific physiological or behavioural characteristic (biometric). In contrast to number of commercially available biometric systems for human recognition in the market today, there is no such a biometric system for plant recognition, even though they have many characteristics that are uniquely identifiable at a species level. The goal of the study was to develop a plant species biometric using both global and local features of leaf images. In recent years, various approaches have been proposed for characterizing leaf images. Most of them were based on a global representation of leaf peripheral with Fourier descriptors, polygonal approximations and centroid-contour distance curve. Global representation of leaf shapes does not provide enough information to characterise species uniquely since different species of plants have similar leaf shapes. Others were based on leaf vein extraction using intensity histograms and trained artificial neural network classifiers. Leaf venation extraction is not always possible since it is not always visible in photographic images. This study proposed a novel approach of leaf identification based on feature hierarchies. First, leaves were sorted by their overall shape using shape signatures. Then this sorted list was pruned based on global and local shape descriptors. The consequent biometric was tested using a corpus of 200 leaves from 40 common New Zealand broadleaf plant species which encompass all categories of local information of leaf peripherals. Two novel shape signatures (full-width to length ratio distribution and half-width to length ratio distribution) were proposed and biometric vectors were constructed using both novel shape signatures, complex-coordinates and centroid-distance for comparison. Retrievals were compared and the biometric vector based on full-width to length ratio distribution was found to be the best classifier. Three types of local information of the leaf peripheral (leaf margin coarseness, stem length to blade length ratio and leaf tip curvature) and the global shape descriptor, leaf compactness, were used to prune the list further. The proposed biometric was able to successfully identify the correct species for 37 test images (out of 40). The proposed biometric identified all the test images (100%) correctly if two species were returned compared to the low recall rates of Wang et al. (2003) (30%, if 10 images were returned) and Ye et al. (2004) (71.4%, if top 5 images were returned). The biometric can be strengthened by adding reference images of new species to the database, or by adding more reference images of existing species when the reference images are not enough to cover the leaf shapes.
225

Quantifying Vein Patterns in Growing Leaves

Assaf, Rebecca 16 May 2011 (has links)
How patterns arise from an apparently uniform group of cells is one of the classical problems in developmental biology. The mechanism is complicated by the fact that patterning occurs on a growing medium. Therefore, changes in an organism’s size and shape affect the patterning processes. In turn, patterning itself may affect growth. This interaction between growth and patterning leads to the generation of complex shapes and structures from simpler ones. Studying such interactions requires the possibility to monitor both processes in vivo. To this end, we developed a new technique to monitor and quantify vein patterning in a growing leaf over time using the leaves of Arabidopsis thaliana as a model system. We used a transgenic line with fluorescent markers associated with the venation. Individual leaves are followed in many samples in vivo through time-lapse imaging. Custom-made software allowed us to extract the leaf surface and vein pattern from images of each leaf at each time point. Then average spatial maps from multiple samples that were generated revealed spatio-temporal gradients. Our quantitative description of wild type vein patterns during leaf development revealed that there is no constant size at which a part of tissue enclosed by vasculature will become irrigated by a new vein. Instead, it seemed that vein formation depends on the growth rate of the tissue. This is the first time that vein patterning in growing leaves was quantified. The techniques developed will later be used to explore the interaction between growth and patterning through a variety of approaches, including mutant analysis, pharmacological treatments and variation of environmental conditions.
226

The evaluation of 391 spring wheat introductions for resistance to stem and leaf rust, loose smut and tan spot

Claude, Pierre-Philippe 03 October 2012 (has links)
Three hundred ninety one (391) spring wheat introductions from Asian, Middle Eastern and Mediteranean areas were screened for resistance to races C17, C20, C25, C49, C53 and C57 of Puccinia qraminis tritici; races 1, 5, 9, 15 and bulks 1, 4 and l0 of Puccinia recondita; races T2, T10, T13 and T39 of Ustilago tritici and to 6 isolates of Drechslera tritici-repentis prevalent in western Canada. Of the 34 introductions resistant to P. graminis tritici, 15 were genetically studied using F2 segregation data derived from the progeny of the crosses involving resistant introductions, their corresponding near isogenic lines and stem rust universal suscepts. Eleven of these were found to carry single Sr genes for resistance, notably, Sr30, Sr13 and Sr15. Of the 70 introductions resistant to P. recondita, 28 were studied and 9 were found to carry known Lr genes for resistance, notably Lr10 and the genes present in RL6057 and RL6061. Twenty two introductions are believed to carry either 1 or 2 unidentified dominant, recessive, partially dominant and/or complementary genes for resistance to either stem or leaf rust. Five introductions were immune and 6 highly resistant to the 4 races of U. tritici. Sixty-nine introductions were resistant to D. tritici-repentis . These were arbitrarily classified into 10 'phenotypic classes' according to their reactions to the 6 isolates used.
227

The genetics of leaf rust resistance in the durably resistant wheat cultivar ‘Toropi’

Barcellos Rosa, Silvia 04 January 2013 (has links)
Wheat is infected by leaf rust disease (Puccinia triticina Eriks.) almost everywhere it is cultivated. The dynamic nature of P. triticina populations affects the effective life span of genes conferring leaf rust resistance (Lr genes). Genetic diversity and combinations of Lr genes should be used to achieve durable resistance. Toropi, a Brazilian wheat cultivar, has maintained leaf rust resistance since its release in 1965, suggesting that it is a good candidate for durable resistance. Two recessive complementary adult plant genes were previously described in Toropi. The objective of this study was to characterize and map the sources of resistance present in Toropi. Double haploid (DH) populations developed by crossing the susceptible leaf rust cultivar Thatcher with Toropi were analysed in Canada (Glenlea – 2010 and Portage La Prairie – 2011), New Zealand (Lincoln – 2010 and 2011) and in Brazil (Parana – 2011), and in greenhouse. The leaf rust reactions indicated the presence of at least four leaf rust resistance genes in Toropi: one seedling gene and three adult plant genes. The seedling resistance gene Trp-Se, responsible for immune response in New Zealand, was mapped on chromosome 3D. QTL analyses identified a QTL associated with leaf rust resistance (QLr.crc-5AL.1) on chromosome 5AL, which overlapped with a QTL for stripe rust (QStr.crc-5AL.1) in the same population. This gene, designated Trp1, is believed to be one of the two adult plant complementary partial resistance genes. The position of the Trp-2 is not confirmed yet. One minor race specific adult plant gene, temporarily designated Trp-3, was mapped on 4BL chromosome. The Lr genes in Toropi confer minor effects against leaf rust, except for Trp-Se, which conditioned immunity in New Zealand. However, when the Toropi Lr genes were combined an almost immune response resulted. Toropi had a very good leaf rust resistance in South and North America, and in New Zealand. The molecular markers identified during this project could facilitate the incorporation of the Toropi genes in new cultivars, helping to achieve more diverse and durable wheat.
228

Characterization of Brillouin Scattering Spectrum in LEAF Fiber

Liu, Xuan 06 December 2011 (has links)
Fiber optic sensors are designed to measure various parameters. The distributed fiber optics sensor has been a very promising candidate for the structural health monitoring. In this thesis, we characterized LEAF (Large Effective Area Fiber) fiber’s Brillouin scattering spectrum and investigated its potentiality for the distributed Brillouin temperature and strain sensor. Optical fibers with complex refractive index profiles are applied to improve the Brillouin threshold by varying the Brillouin linewidth. As LEAF fiber has a modified refractive index profile, we investigated its Brillouin linewidth’s dependence on the square of the pump light’s frequency. We verified the Brillouin frequency’s variation with input SOP experimentally for LEAF fiber in the spontaneous regime. This sets a limitation for the frequency resolution of distributed Brillouin sensors. We also realized a simultaneous temperature and strain sensor with LEAF fiber applying the Brillouin optical time domain analysis. Based on the direct detection of LEAF beat frequencies, a simultaneous strain and temperature sensor was demonstrated.
229

Ecophysiological leaf traits of Cerrado woody plants

Ball, Ronald Aaron 11 1900 (has links)
The Cerrado is a biodiversity hotspot undergoing land conversion with need of broad-extent quantification of species and associated ecosystem function. The effects of species on ecosystems can be tested when functional traits are related to ecosystem properties. The patterns of ecophysiologically-linked leaf traits were characterized with the goals of understanding functional diversity of the above ground biomass for ecosystem characterization and discrimination of this status using remote sensing spectroscopy data. Functional groups of plant life form had more consistently different trait status than taxonomy based groups. Specific leaf area and leaf water content were the most significant traits distinguishing functional groups. Spectral indices from a handheld spectrometer were insufficient to capture the variation of these key traits. Future studies integrating remote sensing to understand the effects of Cerrado functional diversity on ecosystem properties would benefit from incorporating life form functional groups, specific leaf area and leaf water content.
230

スギ落葉有機組成分の生分解(第2報) 2年および3年経過リターの組成分について

川上, 日出國, KAWAKAMI, Hidekuni, 坂野, 弘美, BANNO, Hiroharu, 沓名, 重明, KUTUNA, Sigeaki 03 1900 (has links) (PDF)
農林水産研究情報センターで作成したPDFファイルを使用している。

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