Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 2011 → Physiological and morphological basis for differences in growth, water use and drought resistance among Cercis L. taxa

Ohio State University (2011)

Physiological and morphological basis for differences in growth, water use and drought resistance among Cercis L. taxa

Sternberg, Petra

Titre : Physiological and morphological basis for differences in growth, water use and drought resistance among Cercis L. taxa

Auteur : Sternberg, Petra

Université de soutenance : Ohio State University

Grade : Doctor of Philosophy (PhD) 2012

Résumé partiel
Water is one of the principle factors determining the structure and species composition of the vegetation occupying a given site. Plantings in constructed sites are particularly problematic as urban environments magnify stresses that are common to most landscapes. Often, trees are selected predominantly for their aesthetic contribution to the landscape, with little consideration of their adaptation to the site. Selecting trees with improved drought resistance and reduced water use may be the best strategy to improve survival, growth and health of trees in urban and suburban landscapes. However, the variety of plant characteristics that contribute to drought resistance and the variation in site characteristics makes plant selection for dry sites difficult. Cercis are small to medium sized and often multi-stemmed trees. Cercis canadensis L. is a valuable commerciallyproduced landscape tree in the United States. The aim of this study was to investigate the inter-taxa variation in drought resistance and water use within the genus Cercis, thereby providing information as to their usefulness for plantings in urban landscapes and to facilitate breeding for improved water use and drought resistance. The genus Cercis currently includes ten recognized species native to the warm, northtemperate zones of North America and Eurasia. The exact number of species and their delimitation remains controversial. The first objective was to describe the Cercis taxa to be used in subsequent experiments (Chapters 3 and 4), to compare them to Cercis described in the literature and describe morphological differences that can influence drought resistance. Growth habit and leaf characteristics were measured and principal component analysis employed to describe variation in the observed characteristics. The taxa described were representative of their species and/or variety. Cercis taxa differed widely in their growth habit and leaf characteristics and showed adaption to their native environment. Cercis employed common as well as taxa-specific strategies to deal with similar environmental conditions. The persistence of the leaf characteristics under non-limiting soil moisture conditions indicated that the characteristics typical of the taxa grown in their native environment were under genetic control. The observation that some characteristics on the Eastern North American taxa espressed great variability indicated introgression of these charateristics and that the taxa are still in the process of speciation.

Version intégrale

Page publiée le 13 mai 2012, mise à jour le 4 décembre 2018