AN IMPROVED SOLARDOME SYSTEM FOR EXPOSING PLANTS TO ELEVATED CO2 AND TEMPERATURE

Ventilated Solardomes (hemispherical glasshouses) have been used for 2 0 yr for studying the effects of gaseous pollutants on plants. This pa per describes a computer-operated facility for studying the effects of CO2 x temperature regimes on plants. The eight chambers were set up f or factorial design experiments - with two levels of CO2 (ambient and ambient+340 ppmv), two levels of temperature (ambient and 3 degrees C tracked continuously above ambient) and two replicates of each CO(2)xt emperature treatment. Monitoring of environmental conditions within th e chambers over a 2 yr period has shown highly effective control of CO 2 and temperature regimes. Even with high-quality and u.v.-B transmitt ing glass, the irradiance in the PAR region was reduced by 18 % within the domes. Variation in temperature across the radii of the domes inc reased with higher photosynthetic photon flux density (PPFD). Vapour p ressure deficits (VPDs) in the ambient temperature domes compared well with outside conditions but were higher in the elevated temperature d omes. The watering regime within the domes affected intermittently the relationship between 'dome' and 'outside' VPDs. The Solardome facilit y has been used extensively for studies of the impacts of climate chan ge within the UK Programme on Terrestrial Initiative on Global Environ mental Research (TIGER).