As recently as January 2006 a new publication in the well-reputed journal Nature (Keppler et al., 2006) reported that green plants provide a hitherto unknown source for CH₄. This was indeed a finding that drew much attention by news media as well as by CH₄ research groups around the world. Production of CH₄ in green plant parts per se had not been observed previously in spite of numerous works attempting to quantify the CH₄-emissions strengths of soil-plant ecosystems.Our research questions were: Can we confirm an aerobic CH₄ release? Is the source to CH₄ release a small or large pool? Does CH₄ release also occur at lower temperatures? Does the UV-component in light enhance the CH₄ release?

Results/Conclusions

CH₄-efflux by detached plant material was measured as increase in [CH₄] in 60 ml glass vials, either through time or in comparison with empty control vials. 500 μL of the head space was sampled with a pressure-lock syringe and measured on a FID gas chromatograph. In our study we show that this phenomenon may occur even at low temperatures and that the rate of CH₄ efflux from plant material is strongly dependent on UV-irradiation. Further, we show that the potential for CH₄ efflux from plant material varies between species and that it is indirectly adjusted by endogenous plant and microbial enzymes.