Physiological responses of tomato (Lycopersicon esculentum Mill) cv. Arka Ashish to elevated atmospheric CO₂ under water limiting conditions

The study was conducted to understand the physiological responses of tomato cv. Arka Ashish to 550 ppm elevated CO₂ (EC) and to what extent EC alleviates the adverse effects of water stress at peak flowering stage. The plants grown at EC had significantly higher P_N with decreased stomatal conductance (g_s) and leaf transpiration rate (E) compared to plants grown at 380 ppm ambient CO₂ (AC), irrespective of water supply conditions. Plants grown at EC recorded a lower number of stomata on both adaxial and abaxial surfaces. The plants at EC maintained higher water potential(Ψ _w), instantaneous water use efficiency (iWUE) and lower osmotic potential (Ψ _s) at irrigated and water stress condition. Higher SOD and GR activity was observed at EC compared to the plants grown at AC. Increased number of fruits and fruit weight per plant were observed at EC both at control and water stress condition.