Concepts and Applications of Chlorophyll Fluorescence: A Remote Sensing Perspective

Light energy absorbed by plant chlorophyll pigments is principally utilized for photosynthesis. The surplus energy is dissipated as heat or re-emitted as chlorophyll fluorescence (CF). The CF is wavelength specific and directly linked to the efficiency of the photosystems I and II. Hence, it is one of the few direct assessments of vegetation condition, growth processes, and productivity. The active CF retrievals are computationally simple but lack scalability; hence, passive measurement in terms of solar-induced chlorophyll fluorescence (SIF) from ground-based, airborne, and space-borne instruments is popular for regional or global monitoring of vegetation condition. The retrieval of SIF from upwelling radiance from vegetation canopy, though complex, is one of the promising developments in the field of remote sensing. Significant research works have been done on the instrumentation, measurement, retrieval, and application of CF for crop/vegetation monitoring and assessment. The present book chapter reviews the basic concepts of chlorophyll fluorescence, its measurement, major SIF retrieval techniques and its applications along with future challenges.