Abstract
This work is continuation of the previous report entitled "On the Experimental Manufacture of a Surface Light source for the Excitation of Pigment in Plant Leaves by using Ultraviolet Light Emitting Diodes (LEDs), bulletin of KNCT, vol.42, pp.63-72 (2007)". New excitation light sources for plant pigment are made by using ultraviolet LEDs (NSPU510CS, NICHIA, 375nm) and near-ultraviolet LEDs (NS400L-ERLM, Nitride Semiconductors, 400nm). The emission of visible light region from LEDs which obstructs fluorescence measurement of plant leaves is removed with the optical filters. Measurements of the fluorescence spectra of pothos (Scindapsus aureus) leaves with various chlorophyll contents can be made by means of these LEDs excitation in the same accuracy as the UV laser excitation. By using LED light sources, the measurement of chlorophyll induction kinetics in peanut (Arachis hypogaea L.) leaves is performed without damage to the leaf surface. In addition, the chlorophyll fluorescence is strongly observed by the near-ultraviolet LED excitation. These LED light sources can be used to measure the plant fluorescence as a substitute for laser light sources.
