Does lateral CO2 diffusion inside leaves from shaded to illuminated leaf areas affect photosynthesis efficiency?
Roland Pieruschka*,1, Siegfried Jahnke1, Manfred Jensen2, Ulrich Schurr1, 1 Forschungszentrum Jlich, Jlich, Germany2 Universitt Duisburg-Essen, Essen, Germany ABSTRACT- Leaf anatomy affects lateral gas diffusion within intercellular air spaces of leaves. In heterobaric leaves, bundle sheath extensions span between lower and upper epidermis and prevent lateral gas transport. Homobaric leaves lack bundle sheath extensions and are characterized by large interconnected intercellular air space with few or no barriers for lateral gas fluxes (Neger 1918). It has been shown that this has consequences for gas exchange measurement (Jahnke & Krewitt 2002). However, we hypothesize that these structure-function relations will also affect gas exchange under natural conditions: distribution of light within a canopy is very heterogeneous, only leaves at the outermost canopy are fully exposed to light, whereas the leaves underneath are often partly shaded. Respiratory processes may dominate in the shad
