Carbon dioxide as a factor regulating the growth dynamics of Juncus bulbosus

Abstract The unusual growth pattern exhibited by Juncus bulbosus L. in a slightly acidic Swedish brown-water lake is due to a CO2 deficit. Decrease in growth rate during the summer can be avoided through CO2 addition in July when CO2 availability is low and epiphytes are thriving. Growth of J. bulbosus in the laboratory is stimulated by CO2 addition up to a concentration somewhat higher than in air (550 ppm), while higher CO2 pressure restrains growth. Root growth refeects the leaf biomass development, but is favoured by elevated CO2 levels even more than the leaves.