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The Global ETD Search service is a free service for researchers
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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 11 to 12 of 12 (0.039 seconds)Spelling suggestions: "subject:"pinus night"" "subject:"pinus niger""
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Integrated approach for addressing assisted population migration programs in forest management to climate change: out-planting performance, genotype by environment interactions, physiological and molecular responseTaïbi, Khaled 27 November 2015 (has links)
Abstract
Forest ecosystems are likely to shift faster in response to climate
change than their maximum natural rate at which they can migrate and
establish. This thesis introduces an interdisciplinary approach to develop a
proactive management strategy towards climate change through assisted
populations’ migration for two pine species; Aleppo pine (Pinus halepensis
Mill.) and Black pine (Pinus nigra ssp. salzmannii).
The main objectives of this study were to (1) evaluate plantation
performance and phenotypic plasticity in the broad context of genotype by
environment interaction (GEI) of these pine seed sources out-planted in
contrasting trial sites to test a hypothetical northwards migration for further
selection under specific conditions, (2) compare the efficiency of joint
regression and Additive Main effect and Multiplicative Interaction (AMMI)
models in elucidating seed sources adaptation patterns in each site then, (3)
explain the basis of the differential response of seed sources to induced
drought and cold stresses through the physiological, metabolomic and
proteomic analyses. This study reproduced real conditions of reforestation
in potential future climatic conditions either in field or under phytotron
controlled conditions.
The selective use of the intraspecific variability was demonstrated to
have a potential contribution to alleviate adverse climate change impacts on
forest ecosystems. For both species, certain seed sources were able to cope
better with specific climate perturbations than others in response to the
northwards shifts; seedlings not belonging to the target site could be
selected for facing current climate irregularities in different environments.
Abstract
Here, provenances moved from slightly different transfer distance metrics
were the best performers. The main problem is the high expected seedlings
mortality due to freezing events and drought stress mainly for seedlings
belonging to warmer provenances. Seed sources phenotypic plasticity was
low to moderate for height and diameter growth and the environmental
effect had a great influence on their performance variation. The AMMI
models demonstrated higher adequacy to analyse complex GEI than the
joint regression analysis. An important finding is that specific adaptation to
adverse environmental conditions was coupled with low phenotypic
plasticity responses.
Differences among Aleppo pine seed sources subjected to induced
drought conditions were significant for chlorophyll fluorescence, pigments
and soluble sugars contents. However, induced cold stress changes
transpiration rate, stomatal conductance, pigments and glucose contents.
The decrease in photosynthesis under drought, unlike to cold stress, was
due to stomatal closure. At the considered metabolomic level, drought
tolerance was related to the decrease of glucose and fructose and the
increase of sucrose contents in needles. However, the cold tolerance was
associated to the decrease of glucose and the increase of sucrose and
fructose contents. At the proteomic level, most of the identified proteins
were related to the transcriptional machinery and sugar metabolism. The
presence of enzyme related to the sulphur amino-acids metabolism could be
the limiting factor for drought stress in Aleppo pine.
Keywords
Assisted population migration, Reforestation, Pinus halepensis, Pinus nigra ssp.
salzmannii, Seed Sources, Out-planting performance, Survival, Growth,
Phenotypic Plasticity, Genotype by Environment Interaction, Adaptation,
Physiology, Metabolomic, Proteomic. / Taïbi, K. (2014). Integrated approach for addressing assisted population migration programs in forest management to climate change: out-planting performance, genotype by environment interactions, physiological and molecular response [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48467 / TESIS
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Ausgewählte Eigenschaften des Sporopollenins der KieferBohne, Guido 27 February 2007 (has links)
Gegenstand der Arbeit sind Zusammenhänge zwischen physikochemischen Eigenschaften und Funktionen der Exine bei Ausbreitung, Bestäubung und Befruchtung. Dabei bewährte sich der Einsatz der 3-kammrigen Sporopolleninkapseln (Zentralkapsel und Sacci) in der Permeationschromatographie. Sowohl kinetisch bedingte chromatographische Dispersion kleiner Moleküle als auch Konzentrationsänderungen von Zuckern und Dextranmolekülen im Medium wurden zur Bestimmung von Permeabilitätskoeffizienten der Nexine genutzt. Die Wasserabsorptionskapazität von Exinefragmenten und die hydraulische Leitfähigkeit der Nexine wurden anhand von Konzentrationsänderungen ausgeschlossener Dextranmoleküle ermittelt. Das Tectum der saccalen Sexine ist eine Mikrofiltermembran mit scharfer Trenngrenze im Submikrometerbereich; daher werden an den Sacci nur Hydrokolloide mit Stokes''schen Radius über 100 nm (z.B. aus nativem Dextran) ausgeschlossen. Die Nexine ist eine nicht-ideale Umkehrosmose-Membran, die in Zucker- und Salzlösungen hohe Reflexionskoeffizienten zeigt; zusätzlich besitzt sie wenige große Poren, die den Austausch von Zuckern und selbst kleinen Polymermolekülen ermöglichen. Die hydraulische Leitfähigkeit der Nexine liegt im Größenbereich derjenigen von Plasmamembranen (0,39-0,48 µm s-1 MPa-1); die Ergebnisse zeigen, dass die Exine weder die Nährstoffaufnahme des Sporoplasten aus der lokulären Flüssigkeit noch dessen rasche Rehydratation in der Mikropyle behindert. Die Einfaltungen der distalen Nexine (oberhalb der Sacci) und die Omega-Faltung der Exine zwischen den Sacci (Leptom) bieten beim Quellvorgang Schutz vor zu schneller Flächenausdehnung der Plasmamembran. Der Corpus kann mit konzentrierten Elektrolytlösungen beladen werden. Beim anschließenden osmotischen Schwellen in Wasser reißt die Exine, und der Sporoplast wird mit anhaftender Intine ausgeschleudert. Wasser und andere polare Flüssigkeiten adhärieren stärker als hydrophobe Flüssigkeiten an Sporopollenin. Die Sporopolleninmatrix weist eine hohe Feststoffdichte auf, ist wenig quellfähig (0,18 mL g-1 TM) und deformationsstabil. Dies ermöglicht die Pulverbildung beim Trocknen. / Subject of this thesis are relationships between physicochemical properties and functions of the exine concerning propagation, pollination and fecundation. Here the application of the 3-chambered sporopollenin-microcapsules (central capsule and sacci) in permeation chromatography proved of value. Both the kinetically dependent dispersion of small molecules and changes in concentration of sugars and dextran molecules in the medium were analysed to determine permeability coefficients of the nexine. The water absorption capacity of exine fragments and the hydraulic conductance of the nexine were calculated by means of changes in concentrations of excluded dextran molecules. The tectum of the saccal sexine is a microfiltration membrane with a sharp cut off in the submicrometer range; thus hydrocolloids with Stokes´radii over 100 nm (e.g. from native dextran) are excluded from the sacci. The nexine is a non-ideal reverse osmosis membrane having high reflexion coefficients in sugar and salt solutions; in addition few large pores allow the exchange of sugars and even of small polymers. The hydraulic conductance of the nexine is in the range typically for plasmamembranes (0.39-0.48 µm s-1 MPa-1); the results indicate that the exine does neither obstruct the uptake of nutrients by the sporoplast from the locular fluid nor hinder the rapid rehydration in the micropyle. When rehydrating, the distal foldings of the nexine (above the sacci) and the omega-like folding of the exine between the sacci (leptom), provide protection for the plasmamembrane when its surface area has to increase too rapidly. The corpus can be loaded with a concentrated electrolyte solution. When subsequently transferred into water the exine rupture and the sporoplast along with the intact intine is ejected. Water and other polar liquids adhere stronger to sporopollenin than hydrophobic ones. The matrix of sporopollenin show a high density in its solid content, water absorption capacity is low (0.18 mL g-1 DM) and it is resistant to deformation. This enable the formation of powder while dehydrating.
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