Rice root growth and root exudation were studied using hydroponics under different atmospheric CO 2 concentrations Rice root growth was stimulated significantly by 70% under elevated CO 2 environment Total organic carbon,acetic acid and formic acid exudated per plant in a higher CO 2 concentration environment were significantly higher than those in ambient CO 2 environment,while the amounts expressed as per unit root dry weight showed no significant difference It is expected that the change of rice r...