Rising atmospheric carbon dioxide concentration ([CO2]) significantly influences plant growth, development, and biomass. Increased photosynthesis rate, together with lower stomatal conductance, has been identified as the key factors that stimulate plant growth at elevated [CO2] (e[CO2]). However, variations in photosynthesis and stomatal conductance alone cannot fully explain the dynamic changes in plant growth. Stimulation of photosynthesis at e[CO2] is always associated with post-photosynthetic secondary metabolic processes that include carbon and nitrogen metabolism, cell cycle functions, and hormonal regulation. Most studies have focused on photosynthesis and stomatal conductance in response to e[CO2], despite the emerging evidence of e[CO2]'s role in moderating secondary metabolism in plants. In this review, we briefly discuss the effects of e[CO2] on photosynthesis and stomatal conductance and then focus on the changes in other cellular mechanisms and growth processes at e[CO2] in relation to plant growth and development. Finally, knowledge gaps in understanding plant growth responses to e[CO2] have been identified with the aim of improving crop productivity under a CO2 rich atmosphere.
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