Photosynthetic capacity


Photosynthetic capacity is a measure of the maximum rate at which leaves are able to fix carbon during photosynthesis. It is typically measured as the amount of carbon dioxide that is fixed per metre squared per second, for example as μmol m−2 sec−1.

Limitations

Photosynthetic capacity is limited by carboxylation capacity and electron transport capacity. For example, in high carbon dioxide concentrations or in low light, the plant is not able to regenerate ribulose-1,5-bisphosphate fast enough. So in this case, photosynthetic capacity is limited by electron transport of the light reaction, which generates the NADPH and ATP required for the PCR Cycle, and regeneration of RUBP. On the other hand, in low carbon dioxide concentrations, the capacity of the plant to perform carboxylation is limited by the amount of available carbon dioxide, with plenty of Rubsico left over.¹ Light response, or photosynthesis-irradiance, curves display these relationships.

Current Research

Recent studies have shown that photosynthetic capacity in leaves can be increased with an increase in the number of stomata per leaf. This could be important in further crop development engineering to increase the photosynthetic efficiency through increasing diffusion of carbon dioxide into the plant.²