Stressed crops emit more methane despite the mitigating effects of elevated carbon dioxide
2011
Qaderi, Mirwais M. | Reid, David M.
Recent studies using single environmental variables show that under aerobic conditions terrestrial plants can emit methane (CH₄). However, the effects of multiple environmental factors - as components of global climate change - on aerobic CH₄ emissions have been little studied. We examined the combined effects of temperature, carbon dioxide (CO₂) and watering regime on CH₄ emissions from six commonly cultivated crop species: faba bean, sunflower, pea, canola, barley and wheat. Plants were grown from seeds in controlled-environment growth chambers under two temperature regimes (24°C day/20°C night and 30°C day/26°C night), two CO₂ concentrations (380 and 760µmolmol⁻¹) and two watering regimes (well watered and water stressed). Plants were grown first under 24/20°C for 1 week from sowing, and then placed under experimental conditions for a further week. After the specified time, plant growth, gas exchange and CH₄ emission rates were determined. Our results revealed that higher temperature and water stress significantly enhance CH₄ emissions from plants, whereas elevated CO₂ had the opposite effect and partially reverses the promotive effects of these factors. We suggest that the despite the mitigating effects of rising atmospheric CO₂, CH₄ emission may be higher in the face of ongoing global climate change in warmer and drier environments.
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