Individual and interactive effects of elevated carbon dioxide and ozone on tropical wheat (Triticum aestivum L.) cultivars with special emphasis on ROS generation and activation of antioxidant defence system

摘要

The effects of elevated CO_2 and O_3, singly and in combination were investigated on various physiological, biochemical and yield parameters of two locally grown wheat (Triticum aestivum L.) cultivars (HUW-37 and K-9107) in open top chambers (OTCs). Elevated CO_2 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 O_3 exposure, as compared to their controls. Under elevated CO_2 + O_3, elevated levels of CO_2 modified the plant performance against O_3 in both the cultivars. Elevated CO_2 caused significant increase in economic yield. Exposure to elevated O_3 caused significant reduction in yield and the effect was cultivar-specific. The study concluded that elevated CO_2 ameliorated the negative impact of elevated O_3 and cultivar HUW-37 was more sensitive to elevated O_3 than K-9107.