Carbon dioxide (CO₂) and ozone (O₃) are important greenhouse gases that contribute to global climate change. The effects of elevated CO₂ and/or O₃ on plants remain unclear. Plant responses to mixtures of the two gases at high concentrations are likely to be complex. Previous studies have shown that the ability to tolerate elevated levels of the two gases varies among plant species; physiological adaptability in the face of changing atmospheric composition also differs among taxa. However, the effects of mixtures of the two greenhouse gases on the growth and physiology of bamboo are largely unexplored, even though bamboos are important vegetation elements throughout tropical and subtropical regions of the planet. In this study, we used open-topped chambers (OTCs) to double the concentrations of atmospheric CO₂ and O₃, and examined changes in membrane lipid peroxidation, photosynthetic physiology, and antioxidase activities in Indocalamus decorus leaves. After 103 days of treatment, elevated O₃ depressed net photosynthetic rate (Pn) without changing stomatal function, but caused no significant oxidative damage in the leaves. High levels of antioxidase activities were maintained in the leaves, indicating that this species had a strong tolerance to elevated O₃. Decreases in reactive oxygen content and antioxidase activity in the leaves highlighted the significant positive effects of elevated CO₂ on photosynthesis in I. decorus. When a mixture of both gases was supplied at high concentrations, we detected no oxidative damage, although photosynthetic capacity was reduced. Negative effects of O₃ were very marked during the early part of the treatment period, but the effects of CO₂ were positive. CO₂ mitigated the oxidative damage caused by O₃ and promoted the growth of I. decorus. Thus, I. decorus tolerated the two greenhouse gases, and was able to adapt to elevated CO₂ and O₃ levels. These findings contribute to the current knowledge base on the response of bamboo to global climate change.

Keywords

Antioxidant Enzyme, Carbon Dioxide, Indocalamus decorus, Membrane Lipid Peroxidation, Ozone, Photosynthetic Physiology