The effect of CO₂-free air on light-induced stomatal opening and H⁺-ATPase activity.

Simulations of (A) maximum stomatal opening level, and (B) maximum H⁺-ATPase activity level in air with moderate CO₂ concentration (+CO₂) compared to CO₂-free air (-CO₂) under different light conditions. Red colour indicates red light, blue colour indicates blue light, purple colour indicates dual beam. Darker colours represent air with moderate CO₂, and lighter colours represent CO₂-free air. (A) Stomatal opening is significantly enhanced by CO₂-free air under all light conditions. (B) The H⁺-ATPase activity pattern parallels that of stomatal opening levels in having higher levels in the absence of CO₂.