THE RED EDGE POSITION AND SHAPE AS INDICATORS OF PLANT CHLOROPHYLL CONTENT, BIOMASS AND HYDRIC STATUS

Some red edge parameters in the first derivative reflectance curve (wavelength, amplitude and area of the red edge peak) were studied to evaluate plant chlorophyll content, biomass and Relative Water Content (RWC). Plants of Capsicum annuum and Phaseolus vulgaris under different nitrogen and water availabilities, and plants of Gerbera jamesonii with different hydric status were studied. A high correlation was found between chlorophyll content and the wavelength of the red edge peak (lambda(re)), and between LAI (leaf area index) and the amplitude of the red edge peak (dr(re)), but the area of the red edge peak (SIGMAdr680-780 nm) was the best estimator of LAI. Thus, red edge was found valuable for assessment of plant chlorophyll concentration and LAI, and therefore nutritional status. Water stress also affected dr(re), but only when the stress was well developed.