Effects of Vapor Pressure Difference on Leaf Conductance and Net Photosynthesis of an Emergent Plant, Zizania latifolia

Abstract

Gas exchange was measured for leaves of an emergent plant, Zizania latifolia (GRISEB.) TURCZ grown at an experimental pond. Net photosynthesis per unit leaf area at above light saturation was rather small. Vapor pressure differences between the intercellular spaces in the leaf and the atmosphere (VPD) affected leaf conductance at photosynthetic photon flux densities saturating net photosynthesis. However, VPD did little to impede net photosynthesis in a surplus of light, which is different from certain emergent plants with high photosynthetic activity per unit leaf area such as Oryza sativa L. and Cyperus papyrus L.