Elevated atmospheric CO2concentration and rhizosphere nitrogen fixation in four forage plants

Abstract

Lolium × boucheanum (2n and 4n), Plantago lanceolata, and Pennisetum clandestinum were grown in pots of soil in growth rooms with factorial combinations of 350 or 700 μl/l atmospheric CO2and day/night temperatures of 28/23°C or 18/13°C. Both cultivars of Lolium and P. lanceolata grew faster with elevated CO2but P. clandestinum was unaffected. Rhizosphere nitrogenase activity, assessed by acetylene reduction, was reduced by the 700 μl/l CO2treatment in the tetraploid Lolium but otherwise did not vary significantly with CO2level. © 1994 Taylor & Francis Group, LLC.