Independent effects of blue light and abscisic acid on methane emissions from canola plants grown under sterile conditions

Methane (CH₄) is the second most important anthropogenic greenhouse gas after carbon dioxide (CO₂), with a global warming potential of nearly 34 times higher than CO₂. Earlier studies have shown that plants produce CH₄ under aerobic conditions. However, few studies have measured aerobically-produced CH₄ emissions from plants that were grown under sterile conditions. It is therefore important to measure plant-derived CH₄ and determine the new driving factors of its emissions. We examined the individual and interactive effects of blue light and abscisic acid (ABA) on plant biomass, moisture content and CH₄ emissions of canola (Brassica napus) plants that were grown under sterile conditions. Plants were grown at three blue light irradiances (0, 2 and 4 mW cm⁻²) and supplied with two concentrations of ABA (0 and 100 μmol L⁻¹) for 2 weeks. Methane emissions were measured in gas samples from the culture vessels. Overall, this study revealed that exogenous ABA and supplemental blue light increased CH₄ emissions somewhat independent from each other, but decreased plant biomass. On dry mass basis, blue light increased CH₄ emission. On fresh mass basis, blue light decreased root mass, and ABA application decreased leaf, stem and total mass. On dry mass basis, blue light and ABA decreased root mass. Higher blue light decreased the ABA-applied plant biomass. The ABA-applied plants had decreased moisture content. Methane had many significant relationships with other plant parameters. In conclusion, plants that were exposed to blue light or treated with ABA were stressed and emitted more CH₄ than the non-stressed plants.