Individual and interactive effects of elevated carbon dioxide and ozone on tropical wheat (<i style="mso-bidi-font-style:normal">Triticum aestivum</i> L.) cultivars with special emphasis on ROS generation and activation of antioxidant defence system

Abstract

The effects of elevated CO₂ and O₃, singly and in combination were investigated on various physiological, biochemical and yield parameters of two locally grown wheat (<i style="mso-bidi-font-style:normal">Triticum aestivum</i> L.) cultivars (HUW-37 and K-9107) in open top chambers (OTCs). Elevated CO₂ stimulated photosynthetic rate (Ps) and F_v/F_m ratio and reduced the stomatal conductance (g_s). Reactive oxygen species, lipid peroxidation, anti-oxidative enzymes, ascorbic acid and total phenolics were higher, whereas Ps, g_s, F_v/F_m, protein and photosynthetic pigments were reduced in elevated O₃ exposure, as compared to their controls. Under elevated CO₂+ O₃, elevated levels of CO₂ modified the plant performance against O₃ in both the cultivars. Elevated CO₂ caused significant increase in economic yield. Exposure to elevated O₃caused significant reduction in yield and the effect was cultivar-specific. The study concluded that elevated CO₂ ameliorated the negative impact of elevated O₃ and cultivar HUW-37 was more sensitive to elevated O₃ than K-9107.