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The Global ETD Search service is a free service for researchers
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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.
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Showing 181 to 190 of 190 (0.042 seconds)| 181 |
Communautés microbiennes de la baie de raisin : Incidence des facteurs biotiques et abiotiques / Microbial communities of the grappe berry : effect of biotic and abiotic factorsMarques Martins, Guilherme 03 July 2012 (has links)
L’étude des communautés microbiennes de la baie de raisin dans des conditions de production à l’échelle de la parcelle montre une dynamique temporelle des populations cultivables, qui se traduit par une augmentation des niveaux de population à partir des stades de début véraison et début maturité. Concernant la communauté bactérienne cultivable, 44 espèces appartenant à 21 genres ont été identifiées. Parmi les huit genres identifiés pour la population fongique, les espèces appartenant au genre Aureobasidium sont les plus abondantes, contrairement aux espèces fermentaires qui restent minoritaires. L’incidence des facteurs biotiques et abiotiques sur différents paramètres de population microbienne tels que la structure, la densité et l’activité métabolique a été analysée. Nous avons observé que les zones climatiques plus fraîches et humides, favorisent le développement des microorganismes. Ces travaux mettent en évidence l’impact écotoxique du cuivre sur la communauté microbienne, en particulier dans sa fraction bactérienne. Le développement de Botrytis cinerea sur la grappe modifie la communauté microbienne des baies de raisin sain : le nombre d’espèces bactériennes augmente ainsi que leur diversité. La communauté bactérienne de la baie de raisin est proche de celle des feuilles d’un point de vue de sa structure, et mais éloignée de celles des écorces et du sol, avec des indices de diversité et de richesse plus faibles. / The study of microbial communities associated with wine grapes under field conditions revealed changes in the size and structure during the berry ripening process, with levels rising gradually and reaching their highest value when the berries were over ripe. During this work several bacteria and fungi species, including fermentative yeast, have been isolated and identified. From cultured bacteria, over 44 species were identified from 21 genera. Concerning fungi population, among eight genera identified, the genus Aureobasidium was the most abundant. Our study reveals the impact of different abiotic and biotic factors over microbial community structure, density and metabolic activity. Comparing different vineyards in the same region, we observed that areas presenting more humid and colder climate favor the growth of microorganisms. Our results also show that the farming system has a clear impact on the microbial community, especially in the bacterial fraction. One of the reasons is the inhibiting effect of copper-based fungicides, frequently used in both organic and conventional farming systems. The presence of Botrytis cinerea in grape berries without visual symptoms of infection can change the microbial community of the grapes, increasing bacterial population density and diversity.
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Improving abiotic and biotic stress tolerance in floriculture cropsSouth, Kaylee 13 November 2020 (has links)
No description available.
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Análisis funcional del gen Ep5C y su implicación en los mecanismos de defensa en plantasCoego González, Alberto 07 May 2008 (has links)
La mancha bacteriana causada por el patógeno Pseudomonas syringae pv. tomato (P. s. tomato) es una de las enfermedades más devastadoras del cultivo del tomate. En este trabajo se demuestra que la sola inhibición de la expresión del gen Ep5C, que codifica una peroxidasa catiónica extracelular, es suficiente para conferir una marcada resistencia a P.s. tomato. Esta inhibición encontrada en las plantas de tomate produce una resistencia que no requiere la activación de las rutas de defensa descritas hasta ahora, controladas por el ácido salicílico y el ácido jasmónico. Así, la inhibición de este gen constituye una nueva herramienta genética para obtener plantas transgénicas resistentes a esta enfermedad. La temprana inducción del gen Ep5C está mediada por el H2O2, una especie reactiva de oxígeno generada durante el curso de u interacciones planta-patógeno. Los mecanismos que controlan la resistencia de las plantas a patógenos necrotrofos constituye uno de los aspectos menos estudiados en la actualidad. La búsqueda de nuevos componentes genéticos que participan en la cascada de señalización de las plantas frente a patógenos constituye uno de los retos de la biología molecular moderna. En este trabajo llevamos a cabo un escrutinio, utilizando plantas transgénicas de Arabidopsis thaliana portadoras del gen de la B-glucoronidasa (GUS) como gen marcador bajo el control del promotor del gen Ep5C, en busca de mutantes alterados en la expresión de dicho gen. En el presente trabajo presentamos la identificación y caracterización de uno de los mutantes, en concreto el mutante ocp3 (overexpressor of cationic peroxidase 3), el cual presenta expresión constitutiva del gen GUS. Las plantas ocp3 muestran una elevada acumulación de H2O2, y se caracterizan por presentar expresión constitutiva de GST1 y PDF1.2, dos genes marcadores de la respuesta defensiva, pero sin embargo no muestra expresión de PR-1, un gen marcador dependiente de la ruta del ácido salicílico (SA). La característic / Coego González, A. (2006). Análisis funcional del gen Ep5C y su implicación en los mecanismos de defensa en plantas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1972
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Agronomic approaches in yield and quality stability of high oleic sunflowers (Helianthus annuus L.) / Pflanzenbauliche Ansätze zur Ertrags- und Qualitätssicherung bei hochölsäurehaltigen (HO) Sonnenblumen (Helianthus annuus L.)Dilci, Burcin 23 October 2008 (has links)
No description available.
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Growth, fruiting body development and laccase production of selected coprini / Navarro González, MónicaNavarro González, Mónica 30 April 2008 (has links)
No description available.
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Analýza fotografických záznamů nerybí kořisti v potravě vybraných druhů rybožravých ptáků / Analysis of photo-records of non-fish prey in the diet of selected species of fish-eating birdsMach, Jakub January 2021 (has links)
Piscivorous birds are often blamed for causing significant damage to fish stocks. Various methods are used to determine the composition of their food, each of them has limits in its ability to determine the complete food spectrum. This work maps the complete food composition of 14 species of fish-eating birds with a method that is not commonly used. Method used in this work uses analysis of publicly available photos on Google.com. In addition to the complete composition of the food, the species composition of the non-fish part of the prey was also determined, and in the case of the Great Cormorant (Phalacrocorax carbo), also the length of the fishes it catches. The aim of this work is to reveal the usability of this method for these purposes. A total of 2350 retrieved photographs were analyzed. The results obtained by photo analysis are in all cases compared with data in the available literature. For representatives of heron birds (Ardeidae), the analysis of photographs provided good information on the food spectrum of individual birds and on the qualitative composition of the non-fish component. It also provided relatively good information on the diet of the White-tailed Eagle (Haliaeetus albicilla), but the bird part of the prey was slightly underestimated. In the diet of the Great Crested Grebe...
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Chemical composition, ruminal degradability and in vitro digestibility of dry matter and crude protein of dichrostachys cinerea and bauhinia thonningii leaves.Mahwasane, Mulalo Birgit 18 May 2018 (has links)
MSCAGR (Animal Science) / Department of Animal Science / Forage and browse legumes play an important role in sustaining livestock in small holder
farming systems in the tropics, mainly as a result of their contribution to economic and
environmental sustainability of livestock production. The study was conducted to determine the
chemical composition, ruminal degradability and in vitro digestibility of dry matter (DM) and
crude protein (CP) of Dichrostachys cinerea and Bauhinia thonningii leaves. The browse tree
leaves were harvested in the wild in Shayandima, Limpopo province. The leaves were collected,
oven-dried, milled to pass through a 1.0 mm sieve and analysed for chemical composition in the
Animal Science Nutrition Laboratory, at the University of Venda. The browse tree leaves were
analysed for DM nitrogen, neutral detergent fibre (NDF) and acid detergent fibre (ADF).
Approximately 5 g of leaf sample milled to pass through through a 1 mm sieve were placed in
nylon bags (external dimension: 6 × 12 cm, pore size of 41 μm) and incubated in duplicates for
0, 4, 8, 16, 24, 48, 72, 96 and 120 hours periods in the rumen of three cannulated Bonsmara
steers. The residues were then analysed for DM and nitrogen. Parameters to describe the
dynamics of ruminal degradability of DM and CP were obtained by fitting the data on the
exponential equation P = a + b (1 - e-ct) using NEWAY computer program, where “a” is the rapid
degradable fraction, “b” is the slow degradable fraction and “c” is the outflow rate. The in vitro
DM and CP degradability of rumen undegradable residue collected after 24 and 48 hour
incubation was determined by sequential in vitro digestion in pepsin (abomasal) and pancreatin
(small intestine) solutions. DM and CP content differed significantly (P ˂ 0.05). D. cinerea
leaves had higher levels of DM and CP content than B. thonningii leaves. DM and CP
disappearance increased (P < 0.01) as the incubation period increased. There was no
difference (P > 0.05) in soluble fraction ‘a’ and ‘b’ of DM of the two species. The CP
components for both fraction ‘a’ and ‘b’ differed significantly (P < 0.01) for CP among the two
species. There was significant difference (P < 0.01) in post-ruminal digestibility among the two
species. CP digestibility of B. thonningii and D. cinerea leaves was reduced (P < 0.01). In
conclusion, B. thonningii and D. cinerea leaves showed significant difference based on their
fermentation kinetics and in vitro digestibility, suggesting a good nutritional quality which can be
used as protein source for ruminants in dry season and supplement to low-quality diets. / NRF
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Hydrophobins in wood biology and biotechnology / Hydrophobinen in Holz Biologie und BiotechnologiePeddireddi, Sudhakar 28 March 2008 (has links)
No description available.
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A Multidisciplinary Approach to Restoration of Butternut (Juglans cinerea)Andrea N Brennan (9390080) 16 December 2020 (has links)
<div>Anthropogenically driven global change is disrupting ecosystems and habitats of many plant species, straining the ability of native species to survive and reproduce. The overarching goal of this research was to holistically work towards restoration of a threatened tree species by connecting research from different disciplines. In order to do so, the threatened butternut tree (<i>Juglans cinerea</i>) and its hybrids were used as a case study. Hybridization can incorporate stress tolerance in plants and could be a potential restoration tool. Evidence in some wild butternut populations indicates that naturalized hybrids of butternut with Japanese walnut (<i>Juglans ailantifolia</i>) may be more tolerant to butternut canker disease (BCD) than butternut, but this has not been formally tested. Thus, chapter 2 examined potential BCD tolerance within and between unadmixed and hybrid butternut inoculated with two BCD fungal isolates. Differences in canker growth were observed by fungal isolate, which could help to explain some differences in BCD severity found among butternut populations. Smaller and fewer cankers and greater genetic gains were detected in hybrid families, demonstrating that hybrids warrant further evaluation as a possible breeding tool for developing BCD-resistant butternut trees.</div><div>However, even with increased disease tolerance, hybrids must possess similar ecophysiological tolerances to their native progenitor to be an effective replacement. Butternut is extremely cold hardy, but Japanese walnuts are native to a warmer ecosystem, indicating potential disparities in extreme temperature tolerances between the two species and their hybrids. Thus, samples from mature trees were subjected to cold and heat treatments to compare relative extreme temperature tolerances within butternut and between butternut, Japanese walnut, and their hybrids. Within butternut, trees from colder areas exhibited less cold damage than those from warmer areas. Differences in heat damage among provenances occurred but did not follow a clear trend. Butternut exhibited greatest cold tolerance, Japanese walnut exhibited greatest heat tolerance, and hybrids were intermediate. Thus, the utility of hybrids for restoration could be limited at the extremes of the species’ distributions.</div><div>A second, but different type of freeze test was conducted for chapter 4 using seedlings to gain a more nuanced understanding of cold tolerance within butternut and between butternut and its hybrids. No survival or damage differences were detected in butternut provenances, although seedlings from the coldest provenances experienced more delayed budbreak at the two warmest treatments than those from warmer provenances. Interspecific differences were not observed in dieback but were detected in survival and budbreak. The hybrids had greater survival than butternut from warmer provenances at the lowest temperature treatment (-38 °C), but given that temperatures that low are extremely unlikely to occur in those provenances, it is not anticipated to give the hybrids an advantage if planted in those areas. However, the hybrids’ earlier budbreak could limit the success of restoration with these hybrids in the coldest extents of butternut’s range. </div><div>If hybrids, as well as genetically modified (GM) trees, are successfully developed for effective disease tolerance and to serve as an ecologically suitable replacement, success of restoration using hybrids will ultimately depend on those directly responsible for replanting efforts. A survey was administered to land managers in 46 organizations in Indiana to gauge perceptions of hybrid and GM trees, as well as current use of hybrid trees. Land managers had stronger concern for ecological, rather than economic, issues. Agreement was highest for using hybrid and GM trees for “conservation and restoration of at-risk species”, “timber production”, and “non-timber products (fruit, syrup, etc.)”. However, perceptions varied by characteristics, such as concern type, age, and the type of land they managed. Ecological concern and the type of land being managed most strongly predicted current hybrid use. Overall, results indicate the majority of land managers in Indiana would likely be agreeable to recommendations towards using hybrids. However, most nonetheless had strong ecological concerns about their suitability as a native replacement. It is important to note, though, that consistent with the results of previous studies, great variation was seen within the performance and characteristics of the butternut hybrids in chapters 2-4. Thus, it may be possible with careful selection and breeding to harness this variation to develop disease tolerant and ecologically similar hybrids acceptable to land managers.</div>
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Actions of lignocellulolytic enzymes on Abies grandis(grand fir) wood for application in biofuel productionCherdchim, Banyat 27 October 2010 (has links)
No description available.
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