Effects of low atmospheric CO 2 on plants: more than a thing of the past

Abstract

In recent geological time, atmospheric CO 2 concentrations were 25–50% below the current level. Photosynthetic productivity of C 3 plants is substantially reduced at these low CO 2 levels, particularly at higher temperatures and during stress. Acclimation of photosynthesis to reduced CO 2 levels might compensate for some of this inhibition, but plants have a limited capacity to modulate Rubisco and other photosynthetic proteins following CO 2 reduction. Because of this, low CO 2 probably acted as a significant evolutionary agent, selecting plants adapted to CO 2 deficiency. Adaptations to low CO 2 might still exist in plants and might constrain responses to a rising CO 2 concentration.