The Influence of Pruning on Morphological and Architectural Characteristics of Camellia japonica L. in a Tropical Climate

The ornamental qualities of Camellia japonica have long been of interest to horticulturists. The European garden plant market has traditionally been characterized by erect, branched and flowered plants. More recently, a new market linked to increasing urbanization has developed for compact, highly branched and flowered plants to decorate balconies and patios. Two flushes are formed per year in temperate climates, and three years are required to obtain a garden plant. In the humid, tropical climate of Reunion Island, at an altitude of 700 m, three to four flushes are formed in a single growing season. Under these conditions and with no pruning, it is possible to produce an upright plant with a height of 48.5 cm and 7.5 branchings, adapted to the traditional garden market. With two prunings and the same growing period, a compact plant with a height of 25.4 and 17.0 branchings can be produced, adapted to the new balcony-patio market. In both cases, floral induction occurs in November when the nighttime temperature is above 15 degrees C. This research shows that it is possible to generate diversified and innovative forms of Camellia japonica with considerable marketing potential using adapted pruning and under appropriate climatic conditions

Phenotyping progenies for complex architectural traits: a strategy for 1-year-old apple trees (Malus x domestica Borkh.)

International audienceThe aim of this study was to define a methodology for describing architectural traits in a quantitative way on tree descendants. Our strategy was to collect traits related to both tree structural organization, resulting from growth and branching, and tree form and then to select among these traits relevant descriptors on the basis of their genetic parameters. Because the complexity of tree architecture increases with tree age, we chose to describe the trees in the early stages of development. The study was carried out on a 1-year-old apple progeny derived from two parent cultivars with contrasted architecture. A large number of variables were collected at different positions and scales within the trees. Broad-sense heritability and genetic correlations were estimated and the within tree variability was analyzed for variables measured on long sylleptic axillary shoots (LSAS). These results were combined to select heritable and not correlated variables. Finally, the selection of variables proposed combines topological with geometric traits measured on both trunks and LSAS: (1) on the trunk, mean internode length, and number of sylleptic axillary shoots; (2) on axillary shoots, conicity, bending, and number of sylleptic axillary shoots born at order 3. The trees of the progeny were partitioned on the basis of these variables. The putative agronomic interest of the selected variables with respect to the subsequent tree development is discussed

Multiple innovations underpinned branching form diversification in mosses

International audienceBroad-scale evolutionary comparisons have shown that branching forms arose by convergencein vascular plants and bryophytes, but the trajectory of branching form diversificationin bryophytes is unclear. Mosses are the most species-rich bryophyte lineage andtwo sub-groups are circumscribed by alternative reproductive organ placements. In one,reproductive organs form apically, terminating growth of the primary shoot (gametophore)axis. In the other, reproductive organs develop on very short lateral branches. Aswitch from apical to lateral reproductive organ development is proposed to have primedbranching form diversification. Moss gametophores have modular development and each module develops from a singleapical cell. Here we define the architectures of 175 mosses by the number of module classes,branching patterns and the pattern in which similar modules repeat. Using ancestral characterstate reconstruction we identify two stages of architectural diversification. During a first stage there were sequential changes in the module repetition pattern, reproductiveorgan position, branching pattern and the number of module classes. During a secondstage, vegetative changes occurred independently of reproductive fate. The results pinpoint the nature of developmental change priming branching form diversificationin mosses and provide a framework for mechanistic studies of architectural diversificatio

Analyse architecturale des herbacées

National audienc

Analyse architecturale des herbacées cultivées

International audienceSome results of the application of the method of architectural analysis, originally designed for trees, to crop species are reviewed. They are illustrated through a comparison between two species, maize (Zea mays L.) and pea (Pisum sativum L.). It is shown that despite huge apparent differences in physiognomy, similarities in architectural development can be found, and expressed within the framework of architectural analysis. The relevance of these results for architectural modelling, crop ecophysiology and architectural studies is discussed. It is argued that one of the main benefits of an interdisciplinary approach probably is at the inter-specific comparative level, and that it may allow for the development of rather general structure-function architectural models, with a clarification of significant specific traits. (© Inra/Elsevier, Paris.)Cet article présente une illustration des premiers acquis de l’application de l’analyse architecturale, initialement développée pour les ligneux, à des espèces herbacées cultivées, à partir de la comparaison de deux espèces, le maïs (Zea mays L.) et le pois (Pisum sativum L.). Malgré d’évidentes différences physionomiques, des similitudes de développement architectural, correspondant à des concepts d’analyse architecturale, existent. La signification de ces résultats pour la modélisation architecturale, l’agrophysiologie et l’architecture des plantes sont discutées. Il semble que le principal bénéfice d’une telle approche interdisciplinaire réside dans la mise en place d’une écophysiologie développementale comparée (entre espèces). Ceci devrait permettre le développement de modèles structure-fonction architecturaux assez généraux, avec une meilleure identification des caractéristiques spécifiques. (© Inra/Elsevier, Paris.