A New Model for Leaf Photosynthesis Incorporating the Gradients of Light Environment and of Photosynthetic Properties of Chloroplasts within a Leaf

A leaf photosynthesis model was constructed based upon the notion that the leaf photosynthesis is a summation of photosynthesis of each chloroplast under in situ micro-environmental conditions. Intra-leaf light environment was calculated using the values of transmittance and reflectance of leaf tissues reported previously. Simulations of light response curves of whole leaf photosynthesis were carried out for the model leaves with different patterns of gradients in light environment and/or in photosynthetic activities. The results indicate that the higher absorption coefficient of chlorophyll in spongy tissue than in palisade tissue and intra-leaf vertical gradient in photosynthetic activity of the chloroplasts as reported for real dorsiventral leaves are both advantageous to the productivity of the leaf because these properties raise the efficiency of the light utilization.