Biomass production and carbohydrate content of Arabidopsis thaliana at atmospheric CO2 concentrations from 390 to 1680 mu l l(-1)

The concentration dependency of the impact of elevated atmospheric CO2 conc entrations on Arabidopsis thaliana L. was studied. Plants were exposed to n early ambient (390), 560, 810, 1240 and 1680 mu l l(-1) CO2 during the vege tative growth phase for 8 days. Shoot biomass production and dry matter con tent were increased upon exposure to elevated CO2. Maximal increase in shoo t fresh and dry weight was obtained at 560 mu l l(-1) CO2, which was due to a transient stimulation of the relative growth rate for up to 3 days. The shoot starch content increased with increasing CO2 concentrations up to two -fold at 1680 mu l l(-1) CO2, whereas the contents of soluble sugars and ph enolic compounds were hardly affected by elevated CO2. The chlorophyll and carotenoid contents were not substantially affected at elevated CO2 and the chlorophyll a/b ratio remained unaltered. There was no acclimation of phot osynthesis at elevated CO2; the photosynthetic capacity of leaves, which ha d completely developed at elevated CO2 was similar to that of leaves develo ped in ambient air. The possible consequences of an elevated atmospheric CO 2 concentration to Arabidopsis thaliana in its natural habitat is discussed .