Reflectance assessment of canopy CO2 uptake

The potential of using visible and near-infrared reflectance for remote ass essment of plant photosynthetic processes has been developed recently at th e leaf and proximal canopy levels ( Penuelas and Filella 1998). This Letter presents a further step in such development by using visible reflectance t o monitor net CO2 uptake of a whole 4 ha crop field, thus opening the possi bility for applications at larger areas with remote sensing from airborne s ensors.