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Fig. 3. Net photosynthesis (A) of upper-canopy leaves of pot-grown (A) and ground-grown plants (B) exposed to combinations of CO2 and O3 concentrations throughout the growing season in the 1999 experiment. Relative treatment effects on average A are shown as percentage of control (CF-373) in pot-grown (C) and ground-grown plants (D). Ozone treatments were charcoal-filtered (CF) air (24 nmol O3 mol–1) and nonfiltered (NF) air plus O3 (75 nmol O3 mol–1). Carbon dioxide treatments were ambient (373 µmol CO2 mol–1), elevated (699 µmol CO2 mol–1), and high (899 µmol CO2 mol–1, pot-grown plants only). Treatments were CF air-ambient CO2 (CF-373), CF air-elevated CO2 (CF-699), CF air-high CO2 (CF-899), NF air plus O3–ambient CO2 (OZ-373), and NF air plus O3–elevated CO2 (OZ-699). Values are means from three replicate chambers per treatment combination.
