S11 - Session O5 - Impact of mechanical stimulation on Hydrangea macrophylla

Authors: Béra Ley-Ngardigal *, Vincent Guérin, Lydie Huché-Thélier, Nathalie Brouard, Thomas Eveleens, Hanaé Roman, Nathalie Leduc

Plant compactness is a key feature of ornamentals plants grown in containers. It contributes to plant esthetical value, increases plant robustness, reduces culture and storage surfaces and transportation costs for trading. For a long time, chemical growth retardants have been commonly used by growers to control plant growth. To-date, concerns about environmental preservation has led to administrative suppression of several of these products from the market. Alternative methods to chemical control of plant growth are thus urgently needed by producers. Mechanical stimulation mimicking wind impact on wild plants has proven efficient in reducing growth and increasing branching in several species, including ornamentals. Industrial solutions are even available for automated mechanical treatment. Yet, not all plant species respond similarly to a given mechanical treatment and desensitization to mechanical stimulation may occur when too frequent stimulations are applied. Therefore, research need to be carried out to find the efficient protocol that meet growers' objectives for each species. To-date, little is known on Hydrangea and mechanical stimulation in the specie. Using an experimental set-up for mechanical stimulation, we currently investigate the phenotypical and molecular responses of Hydrangea macrophylla plants in order to decipher the mechanisms involved. First results will be presented. Produced by the Common Laboratory MATCH associating the UMR IRHS (INRAE, University of Angers, L'Institut Agro) and Hortensia France, with the support of the ANR (French National Research Agency) and of University of Angers and Hortensia France for BLN PhD grant.