An improved Solardome system for exposing plants to elevated CO₂ and temperature

Ventilated Solardomes (hemispherical glasshouses) have been used for 20 yr for studying the effects of gaseous pollutants on plants. This paper describes a computer-operated facility for studying the effects of CO₂ × temperature regimes on plants. The eight chambers were set up for factorial design experiments - with two levels of CO₂ (ambient and ambient + 340 ppmv), two levels of temperature (ambient and 3 °C tracked continuously above ambient) and two replicates of each CO₂ × temperature treatment. Monitoring of environmental conditions within the chambers over a 2 yr period has shown highly effective control of CO₂ and temperature regimes. Even with high-quality and u.v.-B transmitting glass, the irradiance in the PAR region Was reduced by 18% within the domes. Variation in temperature across the radii of the domes increased with higher photosynthetic photon flux density (PPFD). Vapour pressure deficits CVPDs) in the ambient temperature domes compared well with outside conditions hut were higher in the elevated temperature domes. The watering regime within the domes affected intermittently the relationship between 'dome' and 'outside' VPDs. The Solardome facility has been used extensively for studies of the impacts of climate change within the UK Programme on Terrestrial Initiative on Global Environmental Research (TIGER).