Phenotyping plants by vibrations

Plant vibrations have been studied for many purposes, both at the whole plant scale or at the local organ scale, see for instance in wind induced physical response of trees or crops [1], insect communication through vibration [2] or thigmomorphogenesis [3] . The experimental measurement of vibrational characteristics of plants, such as the frequencies of free motion, has considerably improved in the past ten years thanks to video motion capture techniques and signal processing . Recent tests on Poplar and Arabidopsis showed that these frequencies revealed important information combining the architecture, the geometry and the local mechanical properties of the plant [4] . This led to the idea of using vibrations for phenotyping plants, as a non-destructive, non-contact and fast method. We have developed a way to obtain quickly (less than a minute) a large quantity of information on the dynamics of a plant, more precisely on its dominant vibration modes. The method is based on an excitation by air pulses, a high speed video recording of the motion, and quasi real time signal processing of images to derive the dominant frequency of the captured motion. Tests on water stressed tobacco, on several mutants of Arabidopis thaliana and on mechanically stressed poplar, showed the robustness and performance of the method. More recently an advanced signal processing has been developed that allows extracting several frequencies present simultaneously in the motion, for instance those of leaves. This was tested on poplar and oak foliage. The method is currently under implementation in automatic phenotyping facilities