${\mathrm{C}\mathrm{O}}_2$ is one of the most important factors affecting photosynthesis at normal field conditions. Other factors are equally important for the reaction to occur, but ${\mathrm{C}\mathrm{O}}_2$ concentration fluctuation or lesser availability can completely alter the rate of reaction, which may also lead to photorespiration. The concentration of ${\mathrm{C}\mathrm{O}}_2$ is very low in the atmosphere (between 0.03% and 0.04%)