Measurement of Laser-Induced Fluorescence Decay and Reflectance of Plant Canopies

A new lidar fluoro-sensor, for the remote characterization of the geometry and of the physiological status of plant canopies, is described. It is based on the use of a laser delivering very short pulses (<100 ps) and on the temporal analysis of both fluorescence and backscattered signals. In a first step, the deconvolution of the backscattered signal gives the level and the relative area of leaves illuminated by the laser beam. In a second step, this information on the canopy geometry is used to deduce the mean chlorophyll fluorescence lifetime, that is considered as an indicator of the photosynthetic activity. Field and laboratory measurements performed with the prototype show that the results obtained agree quite well with classical near-contact chlorophyll fluorescence measurements and can bring also information on plant canopy geometry.