Advances in Research on Photosynthesis of Submerged Macrophytes

The submerged macrophytes are higher-level plants derived from land angiosperms that developed a series of changes in morphology and photosynthetic ecophysiology to readapt to living underwater. This paper summarizes the photosynthesis of submerged macrophytes is affected by factors such as light, temperature, pH and inorganic carbon in the water body. Low rates of CO₂ diffusion in water and thick external boundaries hamper the net carbon uptake of submerged macrophyes, so the rate of photosynthesis may often be limited by the supply rate of inorganic carbon. To obtain inorganic carbon, the macrophytes present structural, morphologic, physiologic and biological features, including thin leaf layers with chloroplast, the ability to use HCO₃⁻ and the choice of C₄-like and CAM photosynthetic metabolism. These features behave like carbon-concentrating mechanisms in the submerged macrophytes.