Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2005
Publication Date: July 1, 2005
Citation: Booker, F.L., Fiscus, E.L. 2005. Reduction of ozone flux and damage by elevated CO2 in soybean [abstract]. Plant Biology. p. 101. Technical Abstract: Current ambient ozone concentrations in many regions of the world suppress yields of susceptible crops by 5 to 15% annually. However, rising concentrations of atmospheric CO2 may lessen the detrimental effects of ambient ozone pollution in part by reducing ozone uptake by crop plants. Field studies with open-top chambers at our location indicate a threshold relationship for average midday ozone flux and decreased seed yield in soybean (Glycine max). Twice-ambient levels of CO2 reduced ozone uptake by 27 to 42% in soybean as determined by measurements of midday leaf conductance, whole-plant transpiration, and ozone concentrations. The reduction in ozone flux was associated with the lack of ozone-induced reductions in net photosynthesis, biomass production, and yield in plants treated concurrently with elevated CO2 and ozone. The response appeared unrelated to treatment effects on superoxide dismutase, glutathione reductase, and peroxidase activities. Total ascorbic acid concentration in lower canopy leaves was increased by 28 to 64% by elevated CO2 and ozone but not in upper canopy leaves. Increasing concentrations of atmospheric CO2 will likely ameliorate ozone damage to many crops due to reduced ozone uptake and as yet undetermined additional factors. While this might be seen as a fortunate coincidence, it is difficult to predict how interactions between these factors and other possible changes in global climate will play out. At present, it is reasonable to conclude that ambient ozone detracts from the total crop productivity possible in clean air in many regions of the world.