<p>  </p> <p>Heat stress affects breeder ducks raised in North America and other parts of the world, but the effects of such stress on the progenies is not known. Therefore, the objectives of this study were to investigate: 1) The objectives of this thesis were to first investigate the effect of heat stress or exposure to exogenous glucocorticoid (GC) on fertility, production performance, egg biochemistry, egg quality, and welfare of breeder Pekin ducks. 2) the effects of maternal GC on phenotypic plasticity and behavior of the F1 generation. Three studies were carried out to investigate these objectives.</p> <p>The first experiment was conducted to test the hypothesis that chronic treatment with low levels of either corticosterone or cortisol would alter heterophil to lymphocyte ratio (HLR) and immune organ morphometrics. Further, we wanted to determine if chronic treatment with either GC would elicit an increase in cortisol levels in egg albumen. To test our hypotheses, we implanted silastic capsules subcutaneously under the skin of the neck of adult ducks (n = 5/sex/dose) using propofol anesthesia. Capsules contained corticosterone, cortisol, or empty capsules as controls. Over the course of 2 weeks, blood serum, blood smears, body weights, and egg quality data were collected. After 2 weeks, ducks were euthanized using pentobarbital (FatalPlus, 396 mg/ml/kg) and body weight, weights of spleens, livers, and the number of active follicles were recorded. Blood smears were analyzed for HLR by a lab unaware of the treatment groups. Albumen GC levels were assessed using mass spectrometry. Data were analyzed using a 2- or 3-way ANOVA as appropriate and <em>post hoc </em>with Fishers protected least squares difference (PLSD). There were no treatment effects on egg quality measures or body weight. Corticosterone treatment did elicit an increase in serum corticosterone (p < 0.05), but not cortisol levels, compared to controls in both sexes. Both cortisol and corticosterone treatments increased (p < 0.05) serum levels of cortisol compared to controls. Relative spleen weights were higher (p < 0.05) in hens following corticosterone but not cortisol treatment. No other organs showed any differences among the treatment groups. Both GCs elicited an increase (p < 0.001) in HLR in hens at all time-points over the 2-week treatment period compared to controls. Cortisol, not corticosterone, elicited an increase in HLR for drakes (p < 0.05) compared to controls at day 1 after implants. Chronic treatment with cortisol, but not corticosterone, elicited an increase (p < 0.01) in egg albumen cortisol levels compared to other groups. Corticosterone was not detected in any albumen samples.</p> <p>The goal of our second experiment was to test the hypothesis that heat stress (HS) would alter welfare, egg quality, and morphometrics of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen due to recent exciting findings that cortisol, not corticosterone, is isolated in egg albumen. To test our hypothesis, adult Pekin ducks were randomly assigned to two different rooms at 85% lay with 60 hens and 20 drakes per room. Baseline data including body weight, body condition scores (BCS) (such as footpad quality, eyes, nostrils, feather cleanliness, and feather quality scores), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 350C for 10h/day and to 29.50C for the remaining 14h/day for 3 weeks while the control room was maintained at 220C. Eggs were collected daily, and body weights were taken on days 0 and 21 relative to the onset of heat treatment. BCS were collected weekly. Eggs were collected weekly for quality assessment and albumen glucocorticoid (GCs) levels assessment using mass spectrometry. One week before the exposure to HS, 10 hens and 5 drakes were euthanized and the same number again after 3 weeks of HS or control exposures using pentobarbital and birds necropsied. Body weight, weights of the liver, spleen, and the number of maturing follicles were recorded. Data analyses were done by 2- or 3-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p value ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens while there was no significant difference in the circulating levels of corticosterone in drakes compared to the controls. The circulating levels of cortisol increased significantly at week 1 (p < 0.05), week 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at week 2 and 3 only (p < 0.05) in the drakes compared to the controls. Feather quality scores (p < 0.01), feather cleanliness scores (p < 0.001) and footpad quality scores (p < 0.05) increased significantly in the HS group compared to controls, higher BCS indicate a decline in welfare. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3 and a descriptive decrease in the number of fertile eggs upon candling at 10 days of incubation, numeric decrease hatchability and increase in the number of dead embryos in the HS group after the incubation period. Hens in the HS group showed a significantly decreased BW (p < 0.001), and number of ovarian follicles (p < 0.05) compared to controls. Shell weight decreased significantly at week 1 (p < 0.05) compared to controls. Yolk weight decreased significantly at week 3 (p < 0.01) compared to controls. HS elicited a significant increase in albumen cortisol levels at week 1 (p < 0.05) and week 3 (p < 0.05).</p> <p>The third experiment was conducted to determine if parental exposure to heat stress would impair performance, hypothalamic pituitary adrenal (HPA) axis response, welfare, or behavior of their offspring. To achieve these goals, we treated adult drakes and hens at peak lay to heat stress or control temperature for 3 weeks and incubated eggs collected from the last 3 days of the experiment. A total of 76 ducklings were placed into pens from each parental treatment group: control (CON-F1) and heat stress (HS-F1) and raised as grow-out ducks. Weekly data for body weights, body condition scores (BCS), and novel object test (NOT) were collected weekly. At 3 weeks of age, ducks (n = 6 per treatment group) were subjected to adrenocorticotropic hormone (ACTH) (ACTH/cosyntropin, 0.0625 mg/kg) challenge or vehicle as control. Blood samples were collected from the metatarsal vein into serum-separator tubes at 0, 1, 2, 3, and 4 hours relative to treatment for the determination of serum glucocorticoids. Blood smears were also produced from these same samples to determine heterophil to lymphocyte ratios (HLR). All injected birds were euthanized with pentobarbital on the second day relative to ACTH administration, spleen and bursa were removed and weighed immediately. Duck level analyses were completed using 1-, or 2 -way ANOVA as appropriate. BCS were analyzed using a chi-squared test. We observed that HS-F1 had a lower hatch weight (p < 0.05) compared to CON-F1. However, growth rates during the 5-week grow-out period were not significantly different between the two flocks. NOT (N = 4) analyses showed that the HS-F1 had a greater fear response (P< 0.001) compared to CON-F1. Similarly, an ACTH stimulation test showed that the HS-F1 ducks had significantly heightened corticosterone and HLR responses compared to CON-F1 ducks (p < 0.05). The HS-F1 showed altered baseline and ACTH-stimulated levels of cortisol compared to controls.</p> <p>In conclusion, GC elicit differential effects and although corticosterone has been stated to be the predominant GC in avian species, cortisol may provide critical information to further understand and improve welfare. HS decreased performance, fertility, and productivity of breeder ducks. In addition, HS and exogenous GC elicited a selective deposition of cortisol, not corticosterone, in the egg albumen. The maternal cortisol deposited in eggs alter the hypothalamic-pituitary adrenal (HPA) axis and behavioral responses of the F1 generation. This suggests that maternal hormones can alter the phenotypic plasticity of the offspring and can be used to produce offspring that have better adaptation to the rising temperatures as a result of climate change. Finally, the measure of cortisol in egg albumen can be used as a non-invasive marker of stress.</p>

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Denna rapport utforskar effekterna av värmeböljor i urbana miljöer och utforskar användningen av olika stadsplaneringsverktyg för att mildra dessa effekter. Värmestress och värmerelaterade sjukdomar är betydande risker som orsakas av stigande temperaturer i städer, därmed analyseras gröna, blå och gråa lösningar i syfte att minska uppkomsten av värmeböljor i stadsmiljöer och därmed även minska dessa risker. Studien bygger på en omfattande litteraturstudie samt en fallstudie av Hornsbergskvarteren i Stockholm där en intervju även genomfördes med viktiga nyckelpersoner. Resultaten från studien pekar på att en kombination av gröna, blåa och gråa lösningar kan samverka för att minska temperaturen i stadsmiljöer. Gröna lösningar som parker, trädplanteringar, gröna tak och väggar kan bidra till att sänka temperaturen men också förbättra luftkvaliteten i städer, vilket skapar hälsosammare levnadsmiljöer. Blåa lösningar inkluderar olika vattenfunktioner i städer där denna studie främst fokuserat på effekterna av sjöar, dammar, kanaler och bäckar. Blåa lösningar har visat sig ha varierande effekter för temperaturregleringen i urbana miljöer, vilket indikerar att ytterligare undersökning är nödvändig för att förstå dess fulla effekt. Två aspekter som inte togs i beaktning under litteraturstudien men som uppkom som potentiella blåa lösningar under fallstudien var fontäner samt potentiella lösningar för fördröjning av regnvatten. Effekterna av dessa kan vidare utforskas i framtida studier för att ge en helhetsbild av blåa lösningars effekter i urbana miljöer. Gråa lösningar, såsom användningen av reflekterande material har visat sig bidra till att skapa svalare städer. Sammantaget pekar resultaten på att en tillämpning av gröna, blåa och gråa lösningar är viktiga för att hantera värmeböljor och mildra dess effekter, främst risken för hälsorelaterade problem. Dessa planeringsverktyg är viktiga för att främja hållbar utveckling och skapa resilienta städer. / This report explores the effects of heatwaves in urban environments and examines the use of various urban planning tools to mitigate these effects. Heat stress and heat-related diseases are significant risks caused by rising temperatures in cities, therefore, green, blue, and gray solutions are analyzed to reduce these risks in urban areas. The study is based on a literature review and a case study of the Hornsberg area in Stockholm, on which an interview was also conducted. The results from the study suggest that a combination of green, blue, and gray solutions can work together to reduce temperatures in urban environments. Green solutions such as parks, trees, green roofs and walls can help to lower temperatures but also improve air quality in cities, creating healthier living environments. Blue solutions include various water features in cities, where this study primarily focused on the effects of lakes, ponds, canals and streams. Blue solutions have shown varying effects on temperature regulation in urban environments, which means that further investigation is necessary to understand their full impact. Two aspects not considered during the literature review but which emerged as potential solutions during the case study, were fountains and rainwater retention basins. For these solutions, further studies need to be reviewed. Gray solutions, such as the use of reflective materials, have proven to contribute to cooler cities. Overall, the results indicate that the integration of green, blue, and gray solutions is important for managing heatwaves and mitigating their effects, primarily the risk of health-related issues. These planning tools are important for sustainable development and creating resilient cities.

Diese Dissertation untersucht die Wechselwirkungen zwischen Getreideproduktion und Klimawandel, um Erkenntnisse für eine gezielte Klimaanpassung und -minderung im Getreideanbau zu gewinnen. Ein zentrales Augenmerk liegt auf der Rolle der Genetik (G), Umwelt (E) und Management (M) in Deutschland. Vier Studien adressieren diese Themen: In Studie 1 wurde eine Lebenszyklusanalyse des Winterweizen- und Winterroggenanbaus mit Sortenversuchsdaten über 30 Jahre durchgeführt. Es konnte erstmals bewiesen werden, dass der Züchtungsfortschritt in Deutschland den CFP von Winterweizen und Winterroggen erheblich reduziert hat. In Studie 2 wurden räumlich dynamische Wetterindizes entwickelt, um die Auswirkungen von Hitze und Trockenheit auf Winterweizen mit Praxisertragsdaten zu untersuchen. Es wurden deutliche Unterschiede in der regionalen Ertragswirkung von Hitze und Trockenheitsstress identifiziert. In Studie 3 wurden standortspezifische Einflüsse auf Hitze und Trockenstresstoleranz von Winterweizen und Winterroggen mit Sortenversuchsdaten vertiefend geprüft. Es wurde bewiesen, dass die Bodengüte einen entscheidenden Einfluss auf die abiotische Stresstoleranz hat. Darüber hinaus konnte keine Verbesserung der abiotischen Stresstoleranz durch den Züchtungsfortschritt nachgewiesen werden. In Studie 4 wurde die Rückkopplung des Klimawandels auf die CFP von Winterweizen, Winterroggen und Wintergerste mit Sortenversuchsdaten analysiert. Die Ergebnisse weisen erstmals nach, dass Hitze und Trockenheit die CO2-Emissionen erhöhen. Außerdem wurde gezeigt, dass hohe Bodenqualität zu geringeren Emissionen pro Fläche und einem geringeren CFP führt. Basierend auf den Ergebnissen der vier Studien wurden wichtige Hebel zum Klimaschutz in der Landwirtschaft unter gleichzeitigen Klimaeinflüssen identifiziert. Hier wurden insbesondere Maßnahmen entlang G × E × M hervorgehoben, die hohe und stabile Erträge sowie maximale Input Effizienzen gewährleisten. / This dissertation examines the interactions between cereal production and climate change to gain insights for targeted climate adaptation and mitigation in cereal cultivation. A central focus is on the role of genetics (G), environment (E), and management (M) in Germany. Four studies address these topics: In Study 1, a life cycle assessment of winter wheat and winter rye cultivation was conducted using variety trial data over 30 years. It was demonstrated for the first time that breeding progress in Germany has significantly reduced the carbon footprint (CFP) of winter wheat and winter rye. In Study 2, spatially dynamic weather indices were developed to investigate the effects of heat and drought on winter wheat using on-farm yield data. Significant regional differences in heat and drought stress yield effects were identified across Germany. In Study 3, site-specific influences on heat and drought stress tolerance of winter wheat and winter rye were examined in depth using variety trial data. It was proven that soil quality has a decisive impact on abiotic stress tolerance. Additionally, no improvement in abiotic stress tolerance due to breeding progress was found. In Study 4, the feedback of climate change on the CFP of winter wheat, winter rye, and winter barley was analyzed using variety trial data. The results indicate for the first time that heat and drought increase the CFP of cereal production. It was also shown that high soil quality sites exhibit lower GHG emissions per unit of land (GHGL) and lower CFPs. Based on the results of the four studies, important levers for climate protection in agriculture under simultaneous climate influences were identified. Particularly, measures along G × E × M were emphasized, which ensure high and stable yields as well as maximum input efficiencies.

Sous contraintes industrielles, les micro-organismes sont soumis à différents stress technologiques, liés à leur culture en réacteur de grande taille, altérant leur viabilité et les performances des procédés. Les fluctuations des paramètres physico-chimiques (température, pH, …) sont responsables de cette baisse d’efficacité de la fermentation. Afin de contribuer à l’intensification des performances des procédés de production de bio-éthanol, ce projet de thèse propose d’améliorer la robustesse d’une souche industrielle de Saccharomyces cerevisiae productrice d’alcool vis-à-vis d’un stress environnemental : la température. La stratégie générale de ce projet réside dans l’obtention d’un mutant plus tolérant que la souche sauvage au stress appliqué par abaissement de son taux de décès. Un pilote original de culture en continu a été mis en place, couplant mutagénèse aux UV, générant des modifications génétiques et pression de sélection par des variations de température, permettant la sélection des variants les plus robustes. Un modèle phénoménologique a été développé afin de simuler les cinétiques microbiennes selon le mode de conduite du pilote et d’optimiser les conditions de fonctionnement nécessaires à l’obtention des futurs variants. Ce modèle cinétique fait intervenir l’influence de la température sur les cinétiques de croissance, de décès cellulaire et de production d’éthanol chez Saccharomyces cerevisiae. Ces cinétiques ont été quantifiées expérimentalement en fonction de la température et des traitements de mutagénèse par UV. Grâce aux conditions obtenues par simulation, des cultures en mode continu ont été réalisées et des variants obtenus ont été caractérisés, en condition de production intensive d’éthanol, sur la base de leurs performances en termes de croissance, de décès et de capacités fermentaires. Cette stratégie a permis de sélectionner un variant possédant une meilleure robustesse vis-à-vis de la température, caractérisé par un taux de décès plus faible que celui de la souche sauvage. Néanmoins ce variant ne se caractérise pas par de meilleures performances fermentaires / Under industrial constraints, microorganisms are exposed to various stresses, due to their cultivation in large scale bioreactor, altering their viability and the performances of bioprocesses. Fluctuations in physico-chemical parameters (temperature, pH, ...) are responsible for this reduction in fermentation efficiency. This Ph.D project intends to improve the robustness of an industrial ethanol producer Saccharomyces cerevisiae strain under heat stress, in order to improve its industrial production of bio-ethanol under temperature fluctuating environment. The strategy of this project is to obtain a mutant more tolerant than the wild type strain to heat stress, possessing a lower death rate. An original continuous culture reactor has been designed, coupling UV mutagenesis (generating genetic modifications) and selection pressure (temperature) to select the most robust variant. A phenomenological model was proposed to simulate microbial kinetics based on the monitoring strategy of the chemostat and to optimize the operating conditions necessary for the generation of variants. This dynamic model involves the impact of the temperature on the kinetics of growth, cell death and ethanol production in Saccharomyces cerevisiae. These kinetics were experimentally quantified as a function of the temperature and the UV treatment. Continuous cultures were carried out under the simulated conditions and some variants were characterized in very high ethanol performance fermentations in terms of growth, death and production performances. This strategy allowed us to select a variant possessing a better thermal robustness characterized by a lower death rate than the wild type strain under heat stress. However, the reduction of the death rate did not translate into better ethanol production performances

Heat stress (HS) induced changes in energy metabolism, proteolysis, lipogenesis, and oxidative balance have meat quality ramifications for livestock. However, several knowledge gaps exist in understanding heat stressed finishing pig physiology and pork quality characteristics and how dietary zinc may ameliorate undesirable outcomes. Research was completed to determine zinc supplementation effects on carcass composition, meat quality, and oxidative stability of fresh and processed pork from pigs subjected to a chronic, cyclic heat stress using a 2×2×2 factorial arrangement of treatments with main effects of environment (HS vs. thermoneutral; TN), added zinc level (50 vs. 130 mg kg^-1 available zinc), and zinc source (inorganic vs. organic). Commercial crossbred mixed-sex pigs (initially 72.0 kg) were group-housed under either TN (18.9-16.7°C) or cycling HS conditions with chronic diurnal heat (30-29°C/26-27°C for 12h:12h) on days 24-71 with acute heat waves (32-33°C/29-30°C for 12h:12h) on days 21-24, 42-45, and 63-65. One representative pig (<i>n</i>=80) per pen was slaughtered on day 64. The HS pigs were lighter bodyweight (<i>P</i>=0.039), yielded lighter carcasses (<i>P</i>=0.011), less last rib backfat (<i>P</i>=0.032), tended to have smaller loin eye area (<i>P</i>=0.062) but similar percent lean in belly center slices (<i>P</i>>0.10). Compared to TN, HS carcasses had higher 24-h pH (<i>P</i>=0.001) and decreased drip loss (<i>P</i>=0.034). Shifts in individual fatty acid profile of sausage product derived from HS carcasses were observed but were of insufficient magnitude to affect iodine value. Initially, sausage from HS carcasses tended (day 0, <i>P</i>=0.071) to have less thiobarbituric acid reactive substances than TN but over a 10-day simulated retail display, no treatment induced lipid oxidation differences (<i>P</i>>0.05) were observed in either sausage or displayed loin chops. Consistent treatment differences in CIE L*a*b* of products throughout the 10-day display were not observed. The relationships between physiological changes in pigs receiving supplemental zinc and their body and ambient temperatures were also investigated. A representative gilt (<i>n</i>=96) was selected for thermal monitoring from each pen of the 2×2×2 treatments plus 4 additional treatments representing 2 intermediate levels of Zn in both environments. Core body temperatures (T_core) during the day 42-45 acute heat wave were continuously recorded via indwelling vaginal thermometers and infrared thermal imaging was used to measure skin temperatures at 12-hour intervals. From a 64-gilt subset of the 2×2×2 treatments, jejunum and ileum samples were collected on day 64 for analysis of villus height, crypt depth, and jejunal gene expression of heat shock proteins (27, 70, 90), occludin, and mucin (MUC2). The HS model induced thermoregulatory changes and increases in T_core (<i>P</i><0.05). Day 42-45 ambient temperature was negatively correlated with expression of HSP-27 (r=-0.42, <i>P</i>=0.047), HSP-90 (r=-0.49, <i>P</i>=0.014), and occludin (r=-0.69, <i>P</i><0.001) in HS pigs. For the organic Zn supplemented pigs, ambient temperature was positively correlated with expression of HSP-27 (r=0.42, <i>P</i>=0.034) and MUC2 (r=0.45, <i>P</i>=0.017) and negatively correlated with villus height in jejunum (r=-0.42, <i>P</i>=0.027) and ileum (r=-0.38, <i>P</i>=0.048). Thermal Circulation Index (measure of heat dissipation) of HS pigs was negatively correlated with their ileum villus height (r=-0.51, <i>P</i>=0.015) and positively correlated with HSP-70 expression (r=0.46, <i>P</i>=0.041). The T_core lacked correlation with most variables. This research demonstrates cyclic HS affects carcass composition and quality but does not appear to reduce display shelf-life of pork as indicated by lack of differences in lipid oxidation and color stability. In this HS model, zinc level or source imparted negligible benefits and thermal correlations with gut integrity characteristics existed for organic zinc supplemented and HS pigs. The degree of heat dissipation by heat stressed pigs appeared to be associated with classic HS damage and intestinal responses which may be useful indicators of HS in the grow-finish pig. Another agricultural challenge is maintaining higher education programming which establishes a successful career trajectory for agricultural students amid generational shifts in attitudes and background experiences. Undergraduates studying Animal Science and/or Agricultural Economics were surveyed to understand their perception of how collegiate curricular, co-curricular, and extracurricular experiences (coursework, club participation, relevant work experience, international experience, advising/mentoring, college life, and professional networking) contribute to their anticipated career success. A best-worst scaling experiment was used to force respondents (<i>n</i>=487) to make unbiased tradeoffs between the collegiate experience attributes. Responses were then related back to additional demographical and experience/perception characteristics of respondents. Students indicated relevant work experience was overwhelmingly the most critical of the 7 factors (57% preference share), followed by professional networking (19%), and coursework (14%). Students solely in a pre-veterinary Animal Science curriculum represented a distinct category of students regarding their beliefs and experiences. Further research is needed to investigate possible disconnects between student perceptions and reality in higher education and agricultural careers.

The study of cis-regulatory elements (CREs) will allow for increased understanding of regulation and lead to insight regarding the mechanisms governing growth, development, health, and disease. The aim of this study was to characterize the de novo in silico predictions of Arabidopsis CREs. Eight synthetic and 30 native promoter-constructs containing an eGFP/GUS reporter protein were generated for cold, genotoxic, heat, osmotic, and salt stress; the circadian clock; ABA signaling; root and epidermis tissue. Constructs were stably transformed into A. thaliana Col-0 and the effects of the CREs were evaluated by in planta stress or tissue assays using GUS expression levels. Results reveal a novel genotoxic element that specifically directs GUS expression in rosette leaves during genotoxic stress. Results also look promising for novel epidermis and root-specific elements. Results of these assays validate the de novo prediction pipeline's ability to identify novel and known CREs related to abiotic stress.

The study of cis-regulatory elements (CREs) will allow for increased understanding of regulation and lead to insight regarding the mechanisms governing growth, development, health, and disease. The aim of this study was to characterize the de novo in silico predictions of Arabidopsis CREs. Eight synthetic and 30 native promoter-constructs containing an eGFP/GUS reporter protein were generated for cold, genotoxic, heat, osmotic, and salt stress; the circadian clock; ABA signaling; root and epidermis tissue. Constructs were stably transformed into A. thaliana Col-0 and the effects of the CREs were evaluated by in planta stress or tissue assays using GUS expression levels. Results reveal a novel genotoxic element that specifically directs GUS expression in rosette leaves during genotoxic stress. Results also look promising for novel epidermis and root-specific elements. Results of these assays validate the de novo prediction pipeline's ability to identify novel and known CREs related to abiotic stress.

L’étude des rendements en blé a mis en évidence une stagnation apparue dans les années 1990, notamment en France, et principalement lié aux stress hydrique et thermique. Dans ce contexte, améliorer la tolérance du blé européen à ces stress est de première importance. Cette étude avait pour but d’étudier le déterminisme génétique de la tolérance à ces stress chez le blé. Pour ce faire, trois populations de blé tendre du CIMMYT combinant des caractères d’adaptation à ces stress ont été cultivées en conditions irriguée, sèche et stress thermique irriguée plusieurs années. Des caractères physiologiques et agronomiques ont été mesurés sur un réseau de 15 essais. Une méthodologie de caractérisation environnementale a été développée et a permis l’identification de six scenarii de stress au sein du réseau. Une covariable environnementale représentative de chacun a été extraite. L’utilisation des modèles de régression factorielles a permis la décomposition de l’interaction génotype x environnement ainsi que la mise en évidence d’une sensibilité différentielle au stress dans le germplasm. Une recherche de QTL multi-environnementale a conduit à la détection de régions génomiques contrôlant les caractères physiologiques et agronomiques ainsi que leurs interactions avec l’environnement. De la caractérisation environnementale à la détection de QTL, cette étude a abouti au développement d’un outil pour les sélectionneurs permettant l’évaluation du potentiel des génotypes face à une gamme d’environnement, mais aussi à l’identification de régions génomiques impliquées dans le contrôle de la tolérance aux stress hydrique et thermique chez le blé tendre. Ceci pourrait améliorer la tolérance à ces stress au sein du germplasm européen. / A stagnation of wheat yield was reported in France and other countries worldwide since the 1990’s, which incriminated mainly drought and heat stress. Improving the European wheat tolerance to them is of first importance. This study aimed to investigate the genetic determinism of the tolerance to such stresses. Three CIMMYT bread wheat populations combining complementary heat and drought adaptive habits were grown in Northern Mexico under irrigated, drought and heat-irrigated treatments from 2011 to 2013. The trial network comprised 15 trials and both physiological and agronomic traits were scored. First, an environmental characterization methodology was developed and resulted in the identification of six main environmental scenarios in the network. A representative environmental covariate was extracted from each of them. Then, a factorial regression model leaded to the dissection of the genotype-by-environment interaction and highlighted differential stress sensitivity of the germplasm. Finally, a multi-environmental QTL detection resulted in the discovery of genomic regions involved in the control of both physiological and agronomic traits and the study of their sensitivity to the environment. From the environmental characterization to the QTL detection, this study resulted in the development of a tool for breeders which may enable the evaluation of the potential of any genotypes in front of a range of environment, but also the identification of genomic regions involved in the control of the tolerance to drought and heat stress in bread wheat. This may help in improving the tolerance of the European bread wheat germplasm to drought and heat stress.

The master´s thesis analyzes influence of direct and reflected solar radiation to heat strain and degradation of thermal insulation in the flat roof construction. In many building was a problem in a significant degradation of thermal insulation made from expanded polystyrene in the vicinity of glass surfaces. To determine the causes of this problem, it was necessary to study and test the properties of building materials and the physical nature of the effect of solar radiation on the building structure. In the introductory section lists the cases of buildings with degradation of thermal insulation and existing knowledge on this issue. The theoretical part describes the technical properties of thermal insulating materials used in the flat roof construction, nature and division of solar radiation, optical laws of light reflection and physical theory to explain the technical thermal behavior of building materials and structures. The last part describes a practical model and analyzing measured data in thermal stress in the flat roof construction. The practical part also determines the importance of different influences configuration structures using to dynamic simulations. At the end of the practical part they are validated theoretical knowledge obtained by analyzing data from a practical model.