Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2003
Publication Date: 11/15/2003
Citation: Booker, F.L., Fiscus, E.L. 2002. Effects of elevated carbon dioxide and ozone on soybean [Glycine max (L.) Merr.] transpiration. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting. Interpretive Summary:
Technical Abstract: A two-year field study was conducted to test the effects of elevated atmospheric CO2 and O3 on whole-plant transpiration in open-top chambers. Soybean (Glycine max, cv. Essex) was grown in 21 l pots and treated with charcoal-filtered air (CF) (18 nmol O3 mol-1) or CF air plus O3 (72 nmol mol-1) in combination with ambient (369 µmol mol-1) or elevated CO2 (718 µmol mol-1) (12 h averages). Plant water loss was monitored by measuring mass changes of potted plants placed on electronic balances in each chamber. Average seasonal whole-plant transpiration was lower by 17% and 28% in plants treated with elevated CO2 and O3, respectively, compared with the control. Water loss from plants treated with both elevated CO2 and O3 was 22% lower than the control. Elevated CO2 treatments suppressed water loss per unit leaf area by 26% whereas water loss per unit leaf area was not significantly affected by the O3-ambient CO2 treatment. Lower transpiration in the elevated CO2 treatments was most likely due to decreased stomatal conductance despite 9% more leaf area. Decreased transpiration in the O3-ambient CO2 treatment was due to suppressed growth and 28% less leaf area. Overall, elevated CO2 counteracted the effects of O3 on water use. These results indicate that elevated CO2 should help to buffer soybean crops against O3 injury and water stress.