Light Transmittance by Apple Leaves and Canopies

Abstract

Light transmittance and reflectance of sun and shade leaves of apple (cv. Golden Delicious) were measured from May to September over the 380-700 nm wavelength range. The mean light absorptance over the range 400-700 nm of both leaf types was in excess of 85%0 except in May, when the leaves were immature and bright green. Sun leaves had a greater specific leaf weight and a lower transmittance than shade leaves. Reflectance of the two leaf types was similar. The proportion of visible to near infra-red radiation decreased beneath hedgerow orchards. Within patches of shade in the visible waveband, the proportion of blue light was increased and that of red decreased.