Question

Under what conditions are C₄ plants superior to C₃?

Answer 1

C₄ plants are superior to C₃ plants under the following conditions: 

C₄ plants can perform photosynthesis at low CO₂ concentrations. C₄ plants show saturation at about 360 L – 1, while C₃ plants show saturation only beyond 450 L – 1. This means that the availability of CO₂ is a limiting factor for C₃ plants; which is not the case with C₄ plants. C₄ plants show a higher temperature optimum but C₃ plants show a lower temperature optimum. So, C₄ plants can carry on photosynthesis even at high temperatures; which is not the case with C₃ plants. C₄ plants are not affected by high oxygen levels in the atmosphere because the plants are not affected by Kranz’s anatomy. Kranz’s anatomy ensures that photorespiration does not take place in C₄ plants. But this is not the case with C₃ plants.