Question

Would you expect the greenhouse effect (an increase in the CO₂ content of the atmosphere) to have a greater effect on C₄ plants or C₃ plants? Why?

Answer 1

Yes, the increase in the CO₂ content of the atmosphere will have greater effect on the C₄ and C₃ plants.

CO₂ of the atmosphere is primarily utilized by the plants to carry on an important anabolic reaction namely, photosynthesis. C₃ plants are in majority on the earth's surface in comparison to the C₄ plants. Most C₄ plants like sorghum, sugarcane, maize, millet etc are economical important plants. Study by a scientist, H. Poorter has been done in this regard. His findings are published in the journal 'Vegetation', his findings are that CO₂ is always a limiting factor for the plant. So, increase in the level of CO₂ is beneficial for the plants as long as we are maintaining a proper green cover on the earth. His findings are that C₃ plants show a proportionate increase of 41% in photosynthesis rate with the 100% increase in CO₂ concentration. However, C₄ plants show a proportionate increase of 22% in the photosynthesis rate with the 100% increase in the CO₂ concentration. Thus, if the green cover is more on the earth's surface then increased CO₂ level is beneficial to the plants, and ultimately it will be more beneficial to us too.