Variability in the rigidity of Coffea canephora Pierre stems determined by acoustic analysis

The physical characteristics of wood are not usually taken into account in the genetic improvement of perennial species cultivated for their fruits or seeds. Yet in coffee trees, stem breakage during harvesting, or lodging during their development are major defects in some cultivars. Such defects are linked to certain mechanical properties of the wood, such as stiffness, which can be characterized by the modulus of elasticity (Eb), a parameter used in the theory of mechanics of solids. The longitudinal Eb of several clones of the species Coffea canephora Pierre was assessed. The Eb was measured using a vibration analysis system developed at CIRAD, the "Bing" system. It is based on an analysis of vibrations caused by a blow to the tip of a piece of wood of known geometry. The Eb obtained in this way revealed substantial variability within the C. canephora study sample. Clone classification according to stiffness made it possible to identify the clones most susceptible to lodging. This technological characteristic of wood is highly heritable (0.64), meaning that effective improvement of this trait is feasible. This parameter could also be used as a predictor of other traits of agronomic interest, such as resistance to borer insects. (Résumé d'auteur