Absorption Spectra of Leaves. I. The Visible Spectrum

Abstract

Absorption and reflection were measured for a number of leaves in the region 400-700 mu. Spectra of normal leaves were compared with those of leaves infiltrated with cold water, heated in boiling water, or dipped in ether, and with the spectra of equivalent quantities of plastid pigments in chloroplast suspension, disintegrated chloroplast and colloidal chlorophyll suspensions, or in methanol extracts. Leaves absorbed 3 or 4 times as much green and about the same blue and red light as extracts. The red band for chlorophyll a in leaves fell at 680 mu while that for extracts was shifted to about 660 mu. Infiltration with cold water reduced light scattering and absorption by the leaf without shifting the bands. Heating shifted the bands toward the blue but not as far in the extracts. Spectra of chloroplast and disintergrated chloroplast suspensions resembled leaves more than extracts, with red peaks still at 680 mu.