IMPACT OF ELEVATED CO2 ON GROWTH AND DEVELOPMENT OF ARABIDOPSIS-THALIANA L

After germination, Arabidopsis thaliana L (cv. Landsberg) was grown at 350 mu l l(-1) (control) or 700 mu l l(-1) (elevated) CO2. Total shoo t biomass at the end of the vegetative growth period was increased by 56% due to a short transient stimulation of the relative growth rate b y elevated CO2 at the onset of the exposure. Thereafter the relative g rowth rate was comparable for both CO2 levels during the remaining veg etative part of the life cycle (0.42 g g(-1) day(-1)). Flowering archi tecture was not affected by elevated CO2, but seed production was 51% higher. Starch content of the shoot was substantially increased upon e xposure to elevated CO2, while the soluble sugar content remained unaf fected. Total nitrogen content, on a dry mass basis, was decreased at elevated CO2 mainly as a result of the increased starch content. Photo synthesis wag stimulated at elevated CO2 and no acclimation of the pho tosynthesis at elevated CO2 was observed. Even though the stimulation of relative growth rate was only temporary, elevated CO2 resulted in a n increased fitness of Arabidopsis thaliana by an increased reproducti ve output.