Conventional and pulse modulation fluorometries: two complementary ways of assessing the physiological activity of plants in relation to global changes

The principles of in vivo chlorophyll fluorescence are summarized. The main features of the two types of fluorometries, the conventional and the pulse amplitude modulation, are outlined. Examples are given of the change in chlorophyll fluorescence parameters of leaves due to variations of temperature and CO₂ atmospheric concentration. The possibility of remote sensing the effects at canopy level is analysed. These examples show that the two described methods constitute complementary ways of assessing physiological activity of plants in the frame of expected variations of environmental conditions