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La raréfaction des ressources en eau associée au changement climatique menace particulièrement la durabilité de la viticulture en climat Méditerranéen. Pour y faire face, la création ou le choix de cépages économes en eau et suffisamment vigoureux en cas de déficit hydrique se présente comme un levier important. Une compréhension approfondie des mécanismes qui gouvernent le maintien de l'état hydrique par la plante est indispensable pour avancer dans cette direction. Dans ce travail les déterminants génétiques et physiologiques de l'utilisation de l'eau ont été explorés chez la vigne. Une descendance F1, issue d'un croisement entre les cépages Syrah et Grenache, a été soumise à deux scénarios hydriques dans des pots (bonne irrigation et déficit modéré) en combinant de nouveaux outils de phénotypage, une démarche de génétique quantitative (pour la détection de QTLs) et des approches physiologiques. L'analyse de l'architecture génétique du maintien du potentiel hydrique par la plante, plus ou moins efficace en cas de déficit hydrique (i.e. iso- ou aniso-hydrique), a révélé un double déterminisme, impliquant non seulement la régulation stomatique de la transpiration mais également le maintien de la conductance hydraulique à travers la plante. Nous avons démontré l'existence d'une action indirecte de l'acide abscissique sur la fermeture stomatique à travers une diminution de la conductance hydraulique dans la feuille avec une variabilité génétique reliée aux comportements iso- ou aniso-hydriques. Par ailleurs, nous avons mis en évidence une variabilité génétique importante de la transpiration nocturne, liée à celle de l'efficience d'utilisation de l'eau, avec des déterminants génétiques et physiologiques que nous avons identifiés. Au-delà de l'utilité des QTLs détectés pour l'amélioration variétale, les résultats originaux de ce travail démontrent l'intérêt de la génétique quantitative pour progresser dans la compréhension de mécanismes physiologiques. / In Mediterranean regions, water scarcity associated with climate change particularly threatens the sustainability of viticulture. Breeding grapevine for reduced water use and maintained production is therefore of major interest. This requires a comprehensive knowledge of the plant physiological responses to drought. In this study we focused on the determinism of transpiration rate as a key trait regulating water status in plant tissues, and on its relationship with water-use efficiency (WUE). We used a F1 progeny from a cross between cultivars Syrah and Grenache and combined powerful phenotyping tools on potted plants submitted to either well-watered or mild deficit conditions with quantitative genetics (for QTL detection) and physiological experiments. Analysis of the genetic control of water status maintenance in the plant, more or less efficient under soil water deficit (i.e. iso- or anisohydric), revealed a dual physiological determinism with a key role for plant hydraulic conductance beside that of stomatal control of transpiration. An indirect role of abscisic acid on stomatal conductance was also evidenced, mediated by the downregulation of leaf hydraulic conductance, with a genetic variability which correlated with genetic variation in iso- or aniso-hydric behaviour. We then revealed wide genetic variations in nocturnal transpiration, which correlated with variations in water use efficiency, and identified corresponding genetic and physiological determinants. In a final switch to the field, we showed consistency between QTLs detected for daytime WUE in pots and in the vineyard. Beyond the potential interest of the QTLs detected in this study for breeding prospects, this work demonstrated the benefits of quantitative genetics to shed light on ecophysiological and physiological processes.

Cette thèse étudie le développement du système financier chinois. Elle dévoile des aspects nouveaux du développement du système financier sur la dernière décennie. Globalement, les résultats montrent que les progrès réalisés vers un système efficient demeurent contrastés. Le premier chapitre montre que le marché obligataire des entreprises non financières est toujours sous influence du gouvernement. Sur la base de cet élément, il est peu probable d’espérer une baisse de la domination du secteur bancaire sur le système financier. Le second chapitre montre que la gouvernance d’entreprise interne reste imparfaite. En analysant les fluctuations des prix des actions au moment de l’annonce d’un changement de P-DG, nous trouvons que le type de propriété de l’entreprise joue une influence majeure sur les conséquences d’une telle décision. Le troisième chapitre révèle que peu de progrès ont été faits en termes de concurrence au sein du secteur bancaire malgré le nombre de nouveaux entrants sur le marché. Cependant, les banques se comportent de façon plus efficiente sur la décennie. Il ne semble pas exister d’arbitrage entre les bénéfices d’une plus grande concurrence et l’efficience du système bancaire en Chine. Le quatrième chapitre montre les effets bénéfiques de la nouvelle réglementation sur les exigences en capital des banques chinoises en termes d’efficience bancaire. Les exigences en capital, en plus de fournir des coussins en capital supplémentaires, apparaissent réduire l’aléa moral entre les actionnaires des banques et leurs créanciers. / This dissertation analyzes the development of the Chinese financial system from different perspectives. It has shed light on the recent advancements of the last decade. Overall, the findings reveal a contrasted picture of the progress achieved towards an efficient system. Chapter 1 has shown that the corporate bond market is still impeded by government influence. Based on this evidence, it is thus very unlikely to expect the banking system to decrease its dominance on the financial system. Chapter 2 also stressed that internal governance mechanisms remain imperfect. By analyzing the market price fluctuations at the time of the announcement of a CEO turnover, we find that ownership type plays a major influence on the expected consequences of such a decision. Chapter 3 revealed that little progress has been made in terms of banking competition despite the increasing number of new entrants in the market. However, banks behaved more efficiently over the decade. No trade-off seems to exist for policy-makers between the benefits of lower banking prices and efficiency of the system. Chapter 4 finally showed the beneficial effects of the capital requirement regulation on bank efficiency in China. Capital requirements, in supplement to provide higher capital buffers, appear to lower moral between banks’ shareholders and debtholders.

Depuis le début des années 90, la gestion des déchets est devenue une gestion de «ressources» dont la valorisation permet de substituer en partie le besoin en ressources naturelles fossiles. Cette valorisation s'accompagne d'une logistique qu'il est nécessaire de planifier sur le territoire afin que les impacts additionnels associés aux activités de gestion ne compensent pas les bénéfices issus de la transformation de la ressource. Par ailleurs, la ressource « déchets » est non uniformément répartie sur le territoire: les gisements ainsi dispersés et disparates ont des implications sur la performance des filières de traitement (leur efficience) et, notamment, sur celle des activités de transport. Afin de prendre en compte cette hétérogénéité spatiale dans l'élaboration et l'évaluation de scénarios de gestion, cette thèse propose une approche territoriale de conception de filières de traitement qui repose sur l'utilisation d'indicateurs de potentiel de valorisation associés aux gisements. Son application au cas d’étude montréalais a permis de cibler à la fois les besoins en termes d'amélioration du système de gestion et les zones territoriales où ces changements devaient apparaître. L'approche développée constitue un premier pas vers un outil d'aide à la décision pour une diversification localisée des filières de traitement. En tenant compte des interactions entre les différents processus des filières (collecte/transport/traitement), elle fournit également un cadre permettant une meilleure coordination globale des activités de gestion des déchets. / Since the early 90's, waste management has become a « resources » management whose recovery can substitute fossil natural resources. The waste processing required can lead to important logistics, which need to be planned so that the additional impacts associated with waste management operations do not offset the benefits arising from the exploitation of the resource. Moreover, waste is a dispersed resource, subject to a great spatial variability (e.g. waste production rate). This has implications on the recovery chains performance and, especially, on the transport-related activities. In order to consider this spatial heterogeneity in waste management planning, this thesis presents a territorial approach to waste recovery chain's design. It relies on the definition of recovery potentials indicators associated to the sources. The application of the approach to the Montreal case allowed finding the areas unfavourable to the management scenarios considered. Determining the causes of low performance allowed targeting the needs in terms of system's improvement and, especially, the areas where these changes needed to happen. Therefore the approach presented in this thesis is the first step towards a decision-making tool for a localized diversification of recovery chains. By including the interactions between the chain's different processes (collection/transport/treatment), it also provides a systemic framework for a better overall planning of waste management activities.

Made available in DSpace on 2014-06-11T19:24:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02-03Bitstream added on 2014-06-13T19:31:34Z : No. of bitstreams: 1 santos_rr_me_botfca.pdf: 739634 bytes, checksum: 22dd4ee99538bf6df069fdde6891965e (MD5) / Universidade Estadual Paulista (UNESP) / O objetivo deste trabalho foi analisar do ponto de vista energético o agroecossistema milho, em sistema de plantio direto, localizado na área III do projeto de assentamento de trabalhadores rurais Pirituba II, no município de Itaberá/SP. A análise energética quantificou todas as operações realizadas, juntamente com suas exigências físicas (quilogramas, litros, horas, metro, hectare, alqueire etc), os insumos utilizados e os grãos produzidos, classificando-os em seus respectivos fluxos, a partir da definição das entradas e saídas de energia, traduzindo-os em equivalentes energéticos e determinando, assim, a matriz energética do agroecossistema. Os índices calóricos utilizados foram os de eficiência cultural e energia cultural líquida. Os resultados desta pesquisa demonstraram a dependência do sistema de fontes de energia industrial, provindas de fertilizantes (44,42%) e agrotóxicos (18,71%), e de energia fóssil do óleo diesel (28,06%). Os valores energéticos, referentes aos tipos de energia direta e indireta, apresentaram grandezas distintas, sendo que a energia indireta (65,60%) representou quase o dobro da energia direta (34,40%) utilizada no sistema, significando que as fontes energéticas utilizadas encontram-se pouco equilibradas. A 2 eficiência cultural encontrada foi de 14,39, apontando que para cada unidade calórica aplicada no agroecossistema o retorno foi de 13,39 unidades e a energia cultural líquida atingiu 115.388,28 MJ x ha-1. Num segundo momento, os dados obtidos foram comparados aos dados publicados por Bueno (2002), que realizou sua pesquisa neste mesmo agroecossistema, ano agrícola e área, porém em duas glebas diferentes que empregavam o sistema de plantio convencional. Na comparação entre os estudos, as entradas culturais de ambos os sistemas foram energeticamente muito semelhantes com 8.619,73 MJ x ha-1 (plantio direto)... / The aim of this work was to proceed, from the energetic point of view, an analysis of a corn agroecosystem, on the direct planting, located at Pirituba II rural workers placement project, Área III, city of Itaberá/SP. The energetic analysis mesured all operations, together with its fisical demands (kilograms, liters, hours, meters, surface measures, etc), the inputs and produced grains, classifying them within their respective flux, based on the definition of energy inputs and outputs, converting them into energetic equivalents and, so, determining the energetic matrix of de agroecosystem. The caloric index used were cultural efficiency and cultural liquid energy. The results showed the dependence of the studied systems on the chemical energy sources, from fertilizers (44,42%), agrotoxics (18,71%), and diesel (28,06%). The energetic values of the direct and indirect energy showed a very big difference between them: indirect energy (65,60%) represented almost twice the direct energy (34,40%) used on the system, what means that the energy sources used in the system are not balanced. The cultural efficiency found was 14,39, pointing that for every caloric unity applied on the agroecosystem, the return was of 13,39 units and cultural liquid energy got to 115.388,28 MJ x ha-1. Later on, obtained data was compared to already existing data in Bueno 4 (2002), who researched corn agroecosystem, in the same agriculture period, at the same area, in two different gleba, with conventional planting system. Comparing both studies, the cultural inputs of both systems were energeticaly almost the same: 8.619,73 MJ x ha-1 (direct planting), e 8.783,78 MJ x ha-1 (convencional planting). The outputs had very different results: 124.008,01 e 79.118,38 MJ x ha-1, respectively. So, we had much more cultural liquid energy on the studied system: 115.388,28 MJ x ha-1, compared... (Complete abstract click electronic access below)

Selon les théoriciens de la transparence, qui de tous horizons disciplinaires, en clament les vertus, l’information financière permet l’équilibre, en remédiant à l’asymétrie de connaissances entre l’émetteur et ses dirigeants, d’une part et les destinataires de l’information financière, d’autre part. Elle lève le voile, combat l’opacité, permet la décision et donc, le jeu même du marché. Les économistes parlent alors d’ « efficience informationnelle » car la circulation fluide et rapide des flux d’information en provenance ou en direction de tous les acteurs des marchés boursiers (émetteurs et dirigeants, opérateurs, actionnaires, autorités de régulation, presse, …) permettraient de fournir à tout instant la meilleure valorisation possible des entreprises cotées compte tenu des informations pertinentes publiquement disponibles. Pour ces raisons, de nombreuses réformes ont été opérées ces dernières années afin de multiplier les obligations d’information à la charge des sociétés cotées. Cependant, force est de constater, au vu de la dernière crise financière, que les marchés peuvent ne pas fonctionner efficacement et évaluer correctement la valeur fondamentale d’un actif financier, alors même que les informations relatives à l’actif sous-jacent sont largement diffusées. De là, se pose la question de la pertinence de la transparence des sociétés cotées. / According to theorists of the transparency who of any disciplinary horizons cry out the virtues, the financial information permits the balance by remedying the asymmetry of knowledge between the company and his management on one hand, and the addressees of the financial information on the other hand. The transparency raises the veil, fights the opaqueness, permit the decision and thus, the game of the market. The economists speak then about “informative efficiency” because the fluid and fast circulation of the flows of information in origin or in the direction of all the actors of stock markets (company, management, operators, shareholders, authorities of regulation, press …) would permit to supply all the time the best possible valuation of listed companies considering the publicly available relevant information. For these reasons, many reforms were operated these last years in order to increase the obligations of information towards listed companies. However, we have to admit, in view of the last financial crisis that markets can not work effectively and estimate correctly the fundamental value of a financial asset while the information relative to the underlying asset is widely broadcasted. From there, we have to ask the question of the relevance of the listed companies’ transparency.

Orientador: Elias José Simon / Banca: Osmar de Carvalho Bueno / Banca: Valeria Comitre / Resumo: O objetivo deste trabalho foi analisar do ponto de vista energético o agroecossistema milho, em sistema de plantio direto, localizado na área III do projeto de assentamento de trabalhadores rurais Pirituba II, no município de Itaberá/SP. A análise energética quantificou todas as operações realizadas, juntamente com suas exigências físicas (quilogramas, litros, horas, metro, hectare, alqueire etc), os insumos utilizados e os grãos produzidos, classificando-os em seus respectivos fluxos, a partir da definição das entradas e saídas de energia, traduzindo-os em equivalentes energéticos e determinando, assim, a matriz energética do agroecossistema. Os índices calóricos utilizados foram os de eficiência cultural e energia cultural líquida. Os resultados desta pesquisa demonstraram a dependência do sistema de fontes de energia industrial, provindas de fertilizantes (44,42%) e agrotóxicos (18,71%), e de energia fóssil do óleo diesel (28,06%). Os valores energéticos, referentes aos tipos de energia direta e indireta, apresentaram grandezas distintas, sendo que a energia indireta (65,60%) representou quase o dobro da energia direta (34,40%) utilizada no sistema, significando que as fontes energéticas utilizadas encontram-se pouco equilibradas. A 2 eficiência cultural encontrada foi de 14,39, apontando que para cada unidade calórica aplicada no agroecossistema o retorno foi de 13,39 unidades e a energia cultural líquida atingiu 115.388,28 MJ x ha-1. Num segundo momento, os dados obtidos foram comparados aos dados publicados por Bueno (2002), que realizou sua pesquisa neste mesmo agroecossistema, ano agrícola e área, porém em duas glebas diferentes que empregavam o sistema de plantio convencional. Na comparação entre os estudos, as entradas culturais de ambos os sistemas foram energeticamente muito semelhantes com 8.619,73 MJ x ha-1 (plantio direto)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this work was to proceed, from the energetic point of view, an analysis of a corn agroecosystem, on the direct planting, located at Pirituba II rural workers placement project, Área III, city of Itaberá/SP. The energetic analysis mesured all operations, together with its fisical demands (kilograms, liters, hours, meters, surface measures, etc), the inputs and produced grains, classifying them within their respective flux, based on the definition of energy inputs and outputs, converting them into energetic equivalents and, so, determining the energetic matrix of de agroecosystem. The caloric index used were cultural efficiency and cultural liquid energy. The results showed the dependence of the studied systems on the chemical energy sources, from fertilizers (44,42%), agrotoxics (18,71%), and diesel (28,06%). The energetic values of the direct and indirect energy showed a very big difference between them: indirect energy (65,60%) represented almost twice the direct energy (34,40%) used on the system, what means that the energy sources used in the system are not balanced. The cultural efficiency found was 14,39, pointing that for every caloric unity applied on the agroecosystem, the return was of 13,39 units and cultural liquid energy got to 115.388,28 MJ x ha-1. Later on, obtained data was compared to already existing data in Bueno 4 (2002), who researched corn agroecosystem, in the same agriculture period, at the same area, in two different gleba, with conventional planting system. Comparing both studies, the cultural inputs of both systems were energeticaly almost the same: 8.619,73 MJ x ha-1 (direct planting), e 8.783,78 MJ x ha-1 (convencional planting). The outputs had very different results: 124.008,01 e 79.118,38 MJ x ha-1, respectively. So, we had much more cultural liquid energy on the studied system: 115.388,28 MJ x ha-1, compared... (Complete abstract click electronic access below) / Mestre

Cette thèse porte sur les choix des investisseurs de long terme en matière de gestion de portefeuille ainsi que sur les primes de risque offertes par le marché financier Français. Les travaux réalisés dans cette thèse se proposent d’apporter un éclairage ainsi que des arguments en faveur des placements à caractère long, risqué et productifs.En matière de gestion de portefeuille, ce travail apporte plusieurs réponses en matière d’allocation d’actifs et de stratégies optimales d’investissement. Tout d’abord, et en se basant sur des indices boursiers actions et obligataires, il s’avère que le marché français est efficient au sens faible et que l’hypothèse de marche aléatoire n’y est pas rejetée. Ce premier résultat implique que les rentabilités anormales que l’on peut mesurer sur ce marché émanent de facteurs de risque à rémunérer et non pas d’anomalies. Ainsi, dans le deuxième article, on démontre une prime de valeur persistante au sein du marché Français sur la période étudiée. Par contre, la prime de taille n’est observable que pour les titre à ratio valeur comptable sur valeur de marché très faibles ou très élevés ainsi que pour les titres ayant une rentabilité cumulée passée élevée. Aussi, investir dans les entreprises à momentum élevé mène toujours à des rentabilités meilleures quelle que soit la taille de l’entreprise considérée. On confirme également que la bonne spécification du portefeuille de marché est sine qua non pour une évaluation correcte des actifs financiers. Dans le troisième article, et dans une optique multi-périodiques de gestion de portefeuille, l’écart-type des rentabilités annualisées des actifs risqués décroit lorsqu’on allonge la période de détention ce qui implique que les gestionnaires de portefeuille tendent à biaiser les allocations vers des actifs plus sûrs et négligent par cela un manque à gagner. Ce travail démontre également que détenir un portefeuille d’actions de petites capitalisations s’avère un placement optimal pour les investisseurs ayant un horizon long. Ces résultats mettent en lumière des règles prudentielles inefficaces du point de vue des assurés d’une part, et, mettent en évidence la nécessité de mesures visant à relancer les marchés pour les petites entreprises et de faciliter leur accès au financement direct d’autre part. / This thesis focuses on long term investments and risk premiums within the French financial market. The results bring evidence supporting placements in long term, risky and productive assets. In terms of portfolio management, this thesis brings several answers regarding the optimal allocation strategies. The first article demonstrates that the French financial market is weak form efficient since we could not reject the random walk hypothesis based on the variance ratio methodology. This first contribution implies that abnormal returns are resulting from risk factors and not from anomalies. Thus, the second article revisits famous asset pricing models and highlights optimal portfolio strategies. We find that value and momentum premiums are persistent in the French market. However, size premium is only observable in extreme book to market and momentum strategies. Moreover, we show that market portfolio choice is sine qua non to models performances and that the latest is surprisingly increasing in times of distress. The third article considers the term structure of risk-return tradeoff. Based on a VAR model, we find that excess annualized standard deviation of stocks excess returns with respect to bonds and bills decreases as we lengthen investment horizon which means that investors may bias their portfolios towards safe assets and neglect additional return. Furthermore, we measured the time diversification effect among stock portfolios by distinguishing small and big capitalizations and prove that it is more profitable to hold small capitalizations than big capitalizations stocks in the long run. These results shed light on inefficient prudential rules from the viewpoint of policyholders on one hand, and, on the other hand, highlight the necessity of implementing measures to revive the markets for small enterprises and facilitate their access to direct financing through the market.

Orientadores: Jose Antenor Pomilio, Saulo Finco / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T03:34:05Z (GMT). No. of bitstreams: 1 Mioni_DanielPasti_M.pdf: 1903299 bytes, checksum: 7343c6fb1cd22aa8df8654d5b9b51852 (MD5) Previous issue date: 2007 / Resumo: Desenvolvemos um amplificador de áudio classe D baseado em moduladores S-?, destinado a aparelhos auditivos, a maioria dos quais utiliza baterias de 1,1V e necessita ter baixo consumo de corrente. Neste trabalho os amplificadores e comparadores foram construídos com inversores CMOS, pois um destes inversores, alimentado com uma tensão de 1,1V, pode consumir uma corrente CC tão baixa quanto 400nA, dependendo das dimensões, e proporcionar alto ganho de tensão quando polarizado em sua região linear de operação. Por estes motivos, podem substituir com vantagem amplificadores operacionais e comparadores em algumas aplicações. Um protótipo deste circuito foi implementado com tecnologia CMOS 0,35µm e alcançou um rendimento de 90% / Abstract: This thesis presents the design of a firstorder S-? audioband power amplifier optimized for hearing aid (HA) amplification. The majority of HAs use a 1.1V battery and require very low current consumption to improve battery life. This work made use of amplifiers and comparators based on CMOS inverters because such an inverter, with a 1.1V battery, can operate on a current as low as 400nA, depending on its dimensions, and provide high voltage gain when biased in their linear region. For these reasons, they can substitute with advantage operational amplifiers in some applications. A prototype of this circuit was implemented in a monolithic chip using 0.35µm CMOS technology and achieved 90% of power efficiency / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Une approche a plusieurs echelles a été développé afin de vérifier si les différences de Δ13C entre les genotypes de peuplier représentaient les différences d'efficience de transpiration à l'échelle des feuilles et la plante entière. Nous avons également vérifié la stabilité des différences génotypiques pour Δ13C dans le temps. Nous avons constaté que les différences génotypiques pour Δ13C pouvaient etre traduites comme la difference d efficience de transpiration a l echelle des feuilles ainsi qu au niveau de la plante entière. L amplitude de la variabilité de l efficience de transpiration a l echelle du plant etait plus grand par rapport à la variabilite a l echelle de la feuille, demontrant le rôle de la perte du carbone lors de la respiration diurne et nocturne (Φc) ainsi que l'eau perdue pendant la transpiration nocturne (Φw). La productivité génotypique augmentait avec l efficience de transpiration chez Populus deltoides × nigra, mais restait stable chez Populus nigra. Les valeurs absolues de l efficience de transpiration observees lors de cette etude etaient plus elevees que chez les autres especes. L enrichissement en 18O de la matiere organique (Δ18Olb) et de l eau (Δ18Olw) des feuilles correlait avec la variation de la conductance stomatique (gs) soit au niveau de l individu ou au niveau génotypique. Lors d une premiere experience nous avons montre que les valeurs de Δ13C restaient stables pour les genotypes Populus deltoides × nigra ages de 5 a 15 ans, avec un classement génotypique particulierement conservé pendant l etude. Toutefois, une seconde experience nous a permis de demontre que des arbres ages de 4 a 7 ans presentaient des valeurs de Δ13C significativement plus faibles que celles observees lors de la premiere experimentation, avec une augmentation progressive de ces valeurs avec l age. Nous concluons que, chez le peuplier, le Δ13C peut etre considere comme un estimateur fiable de l efficience de transpiration a l echelle du plant entier, et le classement genotypique établi chez de jeunes arbres pour Δ13C reste stable avec l'âge. / Up scaling approach was developed to check whether genotype differences in Δ13C represent the differences in transpiration efficiency at leaf and whole plant scale. We also verified the stability genotype difference in Δ13C with age. We found that genotype differences in Δ13C were as such translated as the difference in transpiration efficiency at both leaf and whole plant scale. Magnitude of variability of whole plant transpiration efficiency was higher as compared to at leaf level highlighting the role of carbon lost during photo and dark respiration (Φc) and water lost during night transpiration (Φw). Genotype productivity increased with increase in transpiration efficiency in Populus deltoides × nigra genotypes but remained unchanged in Populus nigra genotypes. Values of whole plant transpiration efficiency were found higher as compared to other species.18O enrichment in both leaf bulk (Δ18Olb) and leaf water (Δ18Olw) reflected variation in stomatal conductance (gs) either at individual level or at genotypic level. In Populus deltoides × nigra genotypes, no increase or decreasing trend was found in Δ13C between the age of 5-15 years and genotypic ranking was conserved over the tested period. However, significantly lower Δ13C values were evidenced between the age of 4-7, which increased with age. We conclude that in poplar, Δ13C is a reliable estimator of whole plant transpiration efficiency and the ranking made in young plant for Δ13C remain stable with age.