Figure 3.

Gradient profile of blue light as relative steric energy flux, % of incident photosynthetically active radiation (PAR), inside a bifacial leaf of Vitis vinifera and measured using a fibre optic microprobe. The leaf was irradiated with collimated light with the adaxial surface facing the light. The probe was inserted from the abaxial leaf side and advanced directly through the leaf until reached the adaxial side, while recording the amount of light (curve in the left part of the figure). See [103] (Figure 3) for more details. (Right) Representation of a typical bifacial leaf. Red arrows show a conceptual representation of surface light reflectance, surface and mesophyll light scattering, and hypothesized light path lengthening. Red lines appear thinner along the depth representing light depletion. The vertical thick lines (left and right) give the thickness (depth) of the leaf (black epidermises; green: mesophyll tissues). Gradient light profile graph (left) is reproduced from [103].