Current availability of ${\mathrm{CO}}_2$ levels in atmosphere is limiting for photosynthesis in:

${\mathrm{C}}_4$ plants show carbon dioxide saturation at about 360 $\mu {\mathrm{lL}}^{-1}$ while ${\mathrm{C}}_3$ responds to increased ${\mathrm{CO}}_2$concentration and saturation is seen only beyond 450 $\mu {\mathrm{lL}}^{-1}$. Thus, current availability of ${\mathrm{CO}}_2$ levels is limiting for photosynthesis in ${\mathrm{C}}_3$ plants. Tomato is a ${\mathrm{C}}_3$ plant while Sorghum, maize and sugarcane are ${\mathrm{C}}_4$ plants.