Question

Is CO2 a limiting factor at normal concentration in the atmosphere in C4 plants?

Answer 1

An increase in CO2 cone. upto 1 % rate of photosynthesis is increased. Higher CO2 concentration is toxic to plant & also closes stomata.

C4 -Plants can photosynthesize at low CO2cone. (upto 10 ppm). "CO2 cone." at which CO2 fixation in photosynthesis is equal to volume" of CO2 released in respiration is "CO2 compensation point", when plant saturated with full light.

CO2 compensation point for C4 plants is 8-10 ppm, while for C3 plants it is 40- 100 ppm