Abstract
Experimental studies of spectral reflectance characteristics and photosynthetic activities of some kinds of tree leaves were carried out. As a result, 1) spectral reflectance characteristics of leaves around the red edge did not show a direct relationship to the photosynthetic activity, 2) “blue shift" of the red edge can be caused only by water deficit in plant leaves without changes of pigment contents, 3) the mechanism by which water deficit cause the “blue shift" of the red edge can be supposed as follows : a dry leaf scatters incident light more than normal leaf because of its plentiful air spaces inside. This scattering should occur mainly at the surface of the leaf, hence less light penetrates into the leaf and absorption bands of pigments become narrower because of decrease of “detour effect."
