Modelling vegetative growth and architecture of Coffea arabica cultivars under water stress

Two Coffea arabica cultivars, IAPAR59 (drought tolerant) and RUBI (drought susceptible), were grown for two years with/without irrigation during the dry seasons. In addition to eco-physiological, anatomical and molecular biology observations, complete descriptions of plant architecture were performed. All architectural data were analysed owing to the AMAPstudio-XPlo software. The methodology for analysing data and the main results are presented here. A first general effect of drought was a decrease of the growth rate (i.e. an increase of the phyllochron) during the dry season. This effect, higher for Rubi than for Iapar59, concerned similarly the main stem and the branches of different ramification orders. Another important response concerned the setting of secondary and tertiary branches on the second year. Globally the treatments had effects on all studied variables but no architectural trait appeared as specifically responsive to temporary droughts. Aside the analyses of cultivars plasticity, the data collected in this study provided matchless information that is currently used for building a functional structural coffee model coupling architectural rules and ecophysiological processes such as the carbon acquisition. The outlines of this so-called Functional Structural Plant Modelling approach are presented as well as its interest for deriving the very primary mechanisms of phenotypic plasticity. (Résumé d'auteur