Morphogenetic analysis of the phenotypic variability of the architectural unit of Hydrangea macrophylla

Hydrangea macrophylla is a ligneous plant that has attracted the attention of many plant breeders and agronomists for the purpose of enhancing its phenotypic plasticity. However, this plasticity was always exploited empirically.Can this plasticity be assessed by a more scientific approach? In this work, the phenotypic variation is analysed via a description of the different development sequences of the plant and by exposing the plant to different contrasted environments. The architectural unit consists of two morphogenetic units: the Vegetative Unit (VU) and the Vegetative and Floral Unit (VFU). They result in four successive development sequences: an organogenetic phase accompanied by continuous growth (sequence A), floral transformation (sequence B), dormancy (sequence C) and flower bloom (sequence D). Under the effect of environmental factors, the formation of the mixed terminal bud (sequence B) provides a considerable source of spatial variability, whereas the absence or presence of dormancy (sequence C) is responsible for a source of temporal variation. The in-depth description of the architectural unit with its morphological components and the characterisation of the four development sequences provide a necessary scientific basis to identify environmental effects on plant development and for the integrated use of its plasticity

Analysis of the Impact of Climatic Conditions on Floral Transformation in Hydrangea macrophylla ‘Leuchtfeuer’

Hydrangea macrophylla is a horticultural plant of considerable commercial interest that has been widely studied with the aim to more effectively control the different stages of its development during production. However, although floral transformation is a key factor underlying the commercial quality of the product, it remains difficult to control despite these efforts. The floral transformation sequence consists of three successive phases: floral induction (B1), floral evocation (B2), and floral organogenesis (B3). The first is a phase of vegetative organogenesis without elongation leading to the formation of a bud composed of eight phytomer primordia under inductive climatic conditions. This work shows that climatic conditions favorable to floral transformation must be continuously applied without interruption throughout phase B1 to ensure the formation of the floral bud in Hydrangea macrophylla ‘Leuchtfeuer’. In the opposite case, floral transformation is stopped and vegetative growth begins once again

Influence d'une ablation totale du feuillage sur l'entree en dormance des bourgeons du noyer (Juglans regia L.)

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Principales caracteristiques de la dormance des bourgeons chez quelques cultivars de noyer: consequences sur la precocite de debourrement et la ramification de l'arbre

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Croissance et ramification de la pousse de l'annee de jeunes noyers (Juglans regia L.)

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Principales caracteristiques de la dormance des bourgeons chez quelques cultivars de noyer : consequences sur la precocite de debourrement et la ramification de l'arbre

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Modification des capacites de croissance des bourgeons du noyer (Juglans regia L.) par application d'une temperature de 4 degres C a differents moments de leur periode de repos apparent.

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Dormance et precocite de debourrement des bourgeons chez les arbres

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