The present study was performed to evaluate the effects of different levels of carbon dioxide (ambient
(382 ppm) and elevated (570 ppm)) and O3 (ambient (50 ppb) and elevated (70 ppb)) on physiological and
biochemical characteristics of potato (Solanum tuberosum L. cv. Kufri chandramukhi) using open top
chambers. Ozone
flux in leaves at 60 days after emergence (DAE) showed a trend in decreasing order as
ACO2 + EO3 > ACO2 + AO3 > ECO2 + EO3 > ECO2 + AO3 > ACO2. Ozone
flux was found to correlate directly with
the plant’s photosynthetic performance and antioxidative response under different combinations of
ambient and elevated CO2 and O3. Maximum O3 flux under ambient CO2 and elevated O3 (ACO2 + EO3)
caused the highest increase in lipid peroxidation and solute leakage and reductions in chlorophyll
content along with photosynthesis rate. Elevated O3 stimulated the activities of superoxide dismutase
(SOD), glutathione reductase (GR) and ascorbate peroxidase (APX) under ambient (ACO2 + EO3) and
elevated CO2 (ECO2 + EO3). However, all these alterations were alleviated by elevated CO2, indicating that
oxidative stress on cell membrane was minimized and depression in photosynthesis rate recovered under
combination of ECO2 + EO3. Elevated CO2 increased antioxidative enzymes and total phenolics in the
leaves under ECO2 + EO3 at 30 DAE, contributing to the protection against O3 induced oxidative stress.
However, at 60 DAE, the protection provided by ECO2 was mainly by reducing the ozone
flux inside the
leaves under ECO2 + EO3. The study suggests that future increase in atmospheric concentrations of CO2
will ameliorate O3 damage to potato due to reduced O3 uptake, increased carbon assimilation and by
enhancing antioxidative property of leaves as an additional factor.