Malting revisited: Germination of barley (Hordeum vulgare L.) is inhibited by both oxygen deficiency and high carbon dioxide concentrations

► Elevated CO2 suppresses the germination of barley seeds despite the presence of O2. ► Fermentative activity of soaked barley seeds increases under high CO2 conditions. ► CO2 impairs the viability of soaked barley seeds. ► CO2 is not toxic to barley seedlings. ► Enhanced CO2 levels cause a rapid and pronounced stress response (GABA accumulation).