Casanova, D.; Bruhn, D.; Mikkelsen, T.

Many studies have found plant leaves to be emitters of CO and CH4. Consensus indicates that CH4 emissions are stimulated by heat and UV, while CO release is additionally stimulated by visible light. The mechanisms producing these emissions are yet to be discovered. To get closer to finding these mechanisms, this study examined whether photosynthesis might influence CO and CH4 leaf emissions. Five plant species of different photosynthesis pathways were analysed for their photosynthesis performance, as well as CO and CH4 emissions under different temperatures and visible light intensities. Findings reveal CO release rates to be positively correlated with light intensity and temperature but suggest a separate dark metabolism. CH4 rates were independent of light intensity and temperature. Much lower CH4 release from excised leaves compared to their connected counterparts, indicates that such is dependent on stomatal opening, supporting the hypothesis that CH4 is dissolved in transpired water. CO release rates are similar between attached and detached leaves, suggesting that CO is produced at epidermal level. Photosynthesis appears to be unrelated to the release of either of these gases.