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Accueil du site → Doctorat → Chine → 2020 → Structure and Hydraulic Conductivity of the Xylem in Branches Affects the Morphology and Photosynthesis Diversity of Leaves in Populus euphratica Oliv

Beijing Forestry University (2020)

Structure and Hydraulic Conductivity of the Xylem in Branches Affects the Morphology and Photosynthesis Diversity of Leaves in Populus euphratica Oliv

李文海;

Titre : Structure and Hydraulic Conductivity of the Xylem in Branches Affects the Morphology and Photosynthesis Diversity of Leaves in Populus euphratica Oliv

Auteur : 李文海;

Grade : Doctoral Dissertation 2020

Université : Beijing Forestry University

Résumé partiel
Populus euphratica Oliv.is a deciduous tree belonging to the genus Populus in the family Salicaceae,which sustains the desert ecosystem and ecological balance.Indeed,P.euphratica is the naturally distributed arbor species in the desert and semi-desert regions of northwestern China.P.euphratica has the characteristics of heterophyll.In order to explore the physiological mechanisms that lead to the morphology and photosynthesis diversity of leaves in P.euphratica,the morphological and anatomical structures of upper(mainly dentate oval leaves)and lower(mainly lanceolate leaves)branches and their leaves were compared by means of paraffin section and optical microscope.Microcomputed tomography(Micro CT)was preliminarily established the technical indexes to scan the fresh branches and leaves of P.euphratica,and the differences in the water-conducting structures of the upper and lower branches were analyzed.The water conductivity(Ks)and the degree of natural embolization(PLC)were measured by HPFM.PMS Model 600 was used to measure the water potential and P-V curves of the branches with leaves.The physiological indices of Pn and Tr in leaves were measured using Li-6400,and the correlation of structural characteristics and water permeability of the two branches on leaf shape and photosynthesis were analyzed,so as to reveal the physiological mechanism of leaf shape change of P.euphratica.The major results were as follows :(1).The morphological features and anatomical differences of upper and lower branches and leaves were analyzed,and the results showed that the upper leaf tended to be xerophytic,with longer petiole,wider leaf width,smaller leaf area and more succulent leaf.upper branch has thicker cuticle and developed vascular bundle sheath structure,the vessel diameter in the upper branches were greater than the lower,and the vessel density in the lower branches was greater than the upper.There are many mucous cells in the upper branch cortex,phloem and pith,which have strong water-retaining ability.Both upper and lower petioles had a large number of parenchyma cells,but the xylem of the upper petiole had a larger diameter and the lower petiole had a smaller diameter

Mots clés : Populus euphratica Oliv.; Diversiform leaves; Xylem vessel structure; Hydraulic characteristics; Photosynthetic characteristics; Ecological adaptability;

Présentation (CNKI)

Page publiée le 15 juin 2021