Optics of a bifacial leaf: 3. Implications for photosynthetic performance

On the basis of a preceding study of light and absorption gradients in a bifacial leaf spatial patterns of photosynthetic rate and photosynthetic saturation have been analyzed for different cases of natural illumination and different distributions of photosynthetic capacity along the depth coordinate. Two quality criteria of the spatially extended leaf photosynthetic performance arose from this analysis. One of them characterizes the range of the acceptable incident quantum fluxes between the lowest economically acceptable one and the highest still not photodamaging one. The second criterion gives the limit for the fractional part of the leaf photosynthetic capacity that can be utilized before the first photoinhibition effect at some depth occurs. It is shown how the range of the acceptable fluxes can be affected by the interplay between light and capacity gradients.