Reflective Light Properties of Tissue Layers in Beech (Fagus sylvatica L.) Leaves

Abstract— Reflective light properties of various tissue layers (adaxial epidermis, palisade and spongy parenchyma and abaxial epidermis) of beech (Fagus sylvatica L.) leaves were measured using paradermal (parallel to epidermis) and transverse sections in the visible and infrared spectral bands by a high-resolution reflectance cytophotometer. Results showed an increment of reflectances of rest leaves following successive removal of paradermal tissue layers (adaxial epidermis, palisade parenchyma, abaxial epidermis). Reflectances of palisade parenchyma with spongy parenchyma and abaxial epidermis increased linearly in the infrared and green spectral bands with increasing chloroplast count. The enhancement of paradermal reflectances with successive removal of paradermal tissue layers was due to various optical effects of tissue/cell layers, whereby removal of paradermal tissue layers containing light absorbers, e.g. chloroplasts/chlorophyll-protein complexes, is of importance. The parabolic relationships found between lateral reflectances and distances of various tissue/cell layers from adaxial epidermis indicated lateral reflectances of the mesophyll to be governed mainly by selective chlorophyll absorb-ances of light according to Lambert-Beer's law.