Some Optical Properties of Leaves of Eight Temperate Forage Grasses

Two instruments are described for the measurement of the reflection and transmission of radiation by grass leaves. The first of these was used to measure the spatial distribution of reflected and transmitted light. It was demonstrated that reflection was influenced by the epidermal structure of a leaf, and that the importance of this layer increased with increasing angle of incidence. The second instrument was used to compare the reflectance and transmittance of leaves of different ages taken from eight temperate grasses. There were significant differences between the grasses in leaf transmittance, and generally the young emerging leaf had a greater transmittance than the fully-expanded leaves. The differences in leaf transmittance could be related to differences in specific leaf weight. There were no significant differences between the species and varieties in leaf reflectance.