Crops such as tomatoes and bell pepper, allowed to grow in a carbon dioxide rich environment, show higher yields because:
(1) They show an increased rate of photosynthesis at higher carbon dioxide concentrations
(2) They can respond to high carbon dioxide conditions even in low light conditions.
(3) They show C4 pathway for cabon fixation at high carbon dioxide is the limiting factor in such plants.
(4) Only carbon dioxide is the limiting factor in such plants