Implications of leaf anatomy in mass and energy exchange between the plant and the atmosphere

Potential effects of leaf thickness on leaf photosynthesis and water use efficiency were studied under a wide range of natural conditions using a modeling technique. The model considers leaf energy balance and photosynthetic capacity as influenced by the mesophyll cell surface area and volume. A greenhouse experiment was conducted to test the model\u27s validity. Soybean (Glycine max (L.) Merr. cv. Amsoy) and velvetleaf (Abutilon theophrasti Medic.) plants were grown under the photosynthetic photon flux densities of 200, 400, and 600 (mu)E/m(\u272)s to induce development of different levels of leaf thickness. Carbon dioxide and water vapor exchange characteristics were monitored on the third and fourth trifoliolates of soybean and the third leaves of velvetleaf plants under sunny and shaded environments. Anatomical parameters of mesophyll cells were evaluated by a stereological method. Verification testing showed good agreement between experimental data and the model predictions. Model computation showed that thick leaves would be more efficient than thin leaves with respect to photosynthetic CO(,2) uptake and water use in many exposed environments. Effects of thickness were dependent upon environmental conditions and exhibited a strong interaction with stomatal resistance