title: Photosynthetic and growth response to fumigation with SO2at elevated CO2for C3and C4plants.
abstract: Six early successional plant species with differing photosynthetic pathways (3 C3species and 3 C4species) were grown at either 300, 600, or 1,200 ppm CO2and at either 0.0 or 0.25 ppm SO2. Total plant growth increased with CO2concentration for the C3species and varied only slightly with CO2for the C4species. Fumigation with SO2caused reduced growth of the C3species at 300 ppm CO2but not at the higher concentrations of CO2. Fumigation with SO2reduced growth of the C4species at high CO2and increased growth at 300 ppm CO2. Leaf area increased with increasing CO2for all plant species. Fumigation with SO2reduced leaf area of C3plants more at low CO2than at high CO2while leaf area of C4plants was reduced more at high CO2than at low CO2. These results support the notion that C3species are more sensitive to SO2fumigation than are C4species at concentrations of CO2equal to that found in normal ambient air. However, the difference in sensitivity to SO2between C3and C4species was found to be reversed at higher concentrations of CO2. A possible explanation for this reversal based upon differences in stomatal response to elevated CO2between C3and C4species is discussed.
authors.affiliation: Institute for Environmental Studies, University of Illinois, 61801, Urbana, IL, USA.
authors.forename: Roger W
authors.initials: RW
authors.lastname: Carlson
authors.affiliation: Department of Botany, University of Illinois, 61801, Urbana, IL, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Bazzaz