We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.
Stark, John M.; Smart, D.; Ritchie, K.; and Bugbee, Bruce, "Evidence that Elevated C02 Levels and Indirectly Increase Rhizosphere Denitrifier Activity" (1997). Biology Faculty Publications. Paper 743.