This work aimed at characterizing xylem hydraulic architecture and at describing its relationships with whole plant water and carbon relations among Populus deltoides × P. nigra hybrids under ...contrasting water regimes. Eight genotypes differing in carbon isotope discrimination were grown in the field in a common garden test. Significant variations were observed between genotypes for all xylem anatomical characteristics, stem or whole-plant hydraulic efficiency and xylem resistance to cavitation. Drought-induced acclimation was observed for xylem structural features and xylem resistance to cavitation, but in a genotype-dependant manner. Under optimal irrigation, a trade-off was observed between hydraulic efficiency and xylem resistance to cavitation or growth performance. These two trade-offs translated into an uncommon positive relationship between xylem resistance to cavitation and growth performance. Under water deficit,this relationship broke down. No relationship could be detected between xylem hydraulics and water-use efficiency estimates. Our results suggest in part that several common relationships that are observed at the between-species level may not necessarily hold true at narrower scales. Further, this work opens up prospects both for identifying the molecular basis of xylem structural acclimation and for breeding strategies.
Cette thèse visait à caractériser l’architecture hydraulique du xylème chez les hybrides de peuplier Populus deltoides × P. nigra et à juger de ses relations avec le fonctionnement hydrique et carboné de l’arbre en conditions d’irrigation contrastées. A cette fin, huit génotypes se distinguant par leur discrimination isotopique vis-à-vis du carbone 13 ont été cultivés en pépinière. Nos travaux ont permis de mettre en évidence d’importantes variations entre génotypes pour les caractéristiques anatomiques du xylème, l’efficience hydraulique de la tige et de la plante entière ainsi que la résistance à la cavitation. Nos travaux démontrent également que l’anatomie et la résistance à la cavitation du xylème s’ajustent aux conditions hydriques du milieu de façon génotype-dépendante. En condition hydrique non limitante, nous avons mis en évidence un compromis entre l’efficience hydraulique et la résistance à la cavitation ou le potentiel de croissance. Ces deux compromis expliquent la relation positive observée entre la résistance à la cavitationet le potentiel de croissance. En condition hydrique limitante, cette relation n’était toutefois plus observable. Aucune relation n’a pu être identifiée entre les propriétés hydrauliques et l’efficience d’utilisation de l’eau. Ces travaux suggèrent que certaines relations couramment observées à l’échelle inter-spécifique ne sont pas nécessairement applicables à des échelles d’étude plus réduites. Ce travail ouvre des perspectives sur le plan fondamental pour l’identification du déterminisme moléculaire à l’origine de la plasticité structurale observée et sur le plan appliqué, pour la création variétale.
Vers de nouveaux critères de sélection pour la populiculture dans un contexte de climat changeant Brignolas , Franck (INRA , Orleans (France). USC 1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales ); Paillassa , Eric (Centre National de la Propriété ForestièreInstitut pour le Développement Forestier, BordeauxBordeaux(France). Service expérimentationsService expérimentations); Fichot , Régis (Université d'Anvers, Wilrijk(Belgique). Département de Biologie, Groupe de Recherche en Ecologie Végétale (PLECO), Campus Drie Eiken)
http://www.foretpriveefrancaise.com/foret-entreprise-n-204-335781.html,
2012, Volume:
204
Publication
Le contexte de changement de climat incite la recherche à identifier de nouveaux critères de sélection pour la populiculture de demain. L’efficience d’utilisation de l’eau, la capacité à maintenir ...une croissance en cas de sécheresse modérée et la résistance à la cavitation sont des caractères très variables entre cultivars et indépendants de leur niveau de productivité. Ils pourraient donc être utilisés pour la sélection de cultivars capables de mieux résister à la sécheresse.
Genotypic variability for productivity, wateruse efficiency and leaf traits in 33 genotypes selected from an F1 progeny of Populus deltoides Bartr. ex Marsh • Populus trichocarpa L. was explored ...under optimal and moderate water-deficit conditions. Saplings of the 33 genotypes were grown in a two-plot open field at INRA Orle´ ans (France) and coppiced every year. A moderate water deficit was induced during two successive years on one plot by withholding irrigation, while the second one remained irrigated (control). Stem biomass and leaf structure (e.g., specific leaf area and leaf area) were measured in 2004 and 2005 and functional leaf traits (e.g., carbon isotope discrimination, D) were measured only in 2004. Tolerance to water deficit was estimated at genotype level as the ability to limit losses in biomass production in water deficit versus control trees. Stem biomass, leaf structure and D displayed a significant genotypic variability whatever the irrigation regime. For all traits, genotype ranks remained stable across years for similar irrigation conditions. Carbon isotope discrimination scaled negatively with productivity and leaf nitrogen content in controls. The most productive genotypes were the least tolerant to moderate water deficit. No relationship was evidenced between D and the level of tolerance to water deficit. The relationships between traits evidenced in this collection of P. deltoides • P. trichocarpa F1 genotypes contrast with the ones that were previously detected in a collection of P. deltoides • Populus nigra L. cultivars tested in the same field trial.
Genotypic variability for productivity, wateruse efficiency and leaf traits in 33 genotypes selected from an F1 progeny of Populus deltoides Bartr. ex Marsh • Populus trichocarpa L. was explored ...under optimal and moderate water-deficit conditions. Saplings of the 33 genotypes were grown in a two-plot open field at INRA Orle´ ans (France) and coppiced every year. A moderate water deficit was induced during two successive years on one plot by withholding irrigation, while the second one remained irrigated (control). Stem biomass and leaf structure (e.g., specific leaf area and leaf area) were measured in 2004 and 2005 and functional leaf traits (e.g., carbon isotope discrimination, D) were measured only in 2004. Tolerance to water deficit was estimated at genotype level as the ability to limit losses in biomass production in water deficit versus control trees. Stem biomass, leaf structure and D displayed a significant genotypic variability whatever the irrigation regime. For all traits, genotype ranks remained stable across years for similar irrigation conditions. Carbon isotope discrimination scaled negatively with productivity and leaf nitrogen content in controls. The most productive genotypes were the least tolerant to moderate water deficit. No relationship was evidenced between D and the level of tolerance to water deficit. The relationships between traits evidenced in this collection of P. deltoides • P. trichocarpa F1 genotypes contrast with the ones that were previously detected in a collection of P. deltoides • Populus nigra L. cultivars tested in the same field trial.
Variations in bulk leaf carbon isotope discrimination, growth and related leaf traits among three Populus nigra L. populations Chamaillard , Sylvain (INRA , Orleans (France). USC 1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales ); Fichot , Régis (INRA , Orleans (France). USC 1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales ); Vincent-Barbaroux , Cécile (INRA , Orleans (France). USC 1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales ) ...
2011
Publication
The ongoing global change could be an additional threat to the establishment and the long-term survival of Populus nigra L., an emblematic European riparian species. With the general aim of gaining ...insights into the adaptive potential of this species, we (i) quantified variations within and among three French P. nigra populations for key physiological attributes, i.e., water-use efficiency (assessed from bulk leaf carbon isotope discrimination, Δ13C), growth performance and related leaf traits, (ii) examined genotype and population by environment interactions, and (iii) explored the relationship between Δ13C and growth. Thirty genotypes were sampled in each of three naturally established populations and grown in two different sites, Orléans (ORL) and Guémené-Penfao (GMN). In ORL, two similar plots were established and different watering regimes were applied in order to test for the drought response. Significant variations were observed for all traits within and among populations irrespective of site and watering. Trait variation was larger within than among populations. The effect of drought was neither genotype- nor population-dependent, contrary to the effect of site. The population ranking was maintained in all sites and watering regimes for the two most complex traits: Δ13C and growth. Moreover, these two traits were unrelated, which indicates that (i) water-use efficiency and growth are largely uncoupled in this species, and (ii) the environmental factors driving genetic structuration for Δ13C and growth act independently. The large variations found within populations combined with the consistent differences among populations suggest a large adaptive potential for P. nigra.
Genotypic variability for productivity, wateruse efficiency and leaf traits in 33 genotypes selected from an F1 progeny of Populus deltoides Bartr. ex Marsh • Populus trichocarpa L. was explored ...under optimal and moderate water-deficit conditions. Saplings of the 33 genotypes were grown in a two-plot open field at INRA Orle´ ans (France) and coppiced every year. A moderate water deficit was induced during two successive years on one plot by withholding irrigation, while the second one remained irrigated (control). Stem biomass and leaf structure (e.g., specific leaf area and leaf area) were measured in 2004 and 2005 and functional leaf traits (e.g., carbon isotope discrimination, D) were measured only in 2004. Tolerance to water deficit was estimated at genotype level as the ability to limit losses in biomass production in water deficit versus control trees. Stem biomass, leaf structure and D displayed a significant genotypic variability whatever the irrigation regime. For all traits, genotype ranks remained stable across years for similar irrigation conditions. Carbon isotope discrimination scaled negatively with productivity and leaf nitrogen content in controls. The most productive genotypes were the least tolerant to moderate water deficit. No relationship was evidenced between D and the level of tolerance to water deficit. The relationships between traits evidenced in this collection of P. deltoides • P. trichocarpa F1 genotypes contrast with the ones that were previously detected in a collection of P. deltoides • Populus nigra L. cultivars tested in the same field trial.
