Growth and root respiration of C4 plants under CO2 enrichment

Respiratory measurements of apical root parts of several C4 plant species (Echinochloa crus-galli var. crus-galli, Setaria pumila and Zea mays DK 312 (Dekalb, USA) subjected to an elevated CO2 regime during growth in climatic chambers or at natural CO2 springs were performed. Biomass production, root respiratory potential and root respiration of Echinochloa was not significantly changed by high atmospheric CO2 treatment in the climatic chambers, compared to ambient CO2 treatment. Root respiratory potential of C4 weeds (Echinochloa crus-galli and Setaria pumila) growing in natural CO2 spring area was not significantly affected by extremelyhigh CO2 in the rhizosphere. Yet, respiratory potential of one and a half month old sown maize seedlings was significantly lower in the roots exposed to naturally elevated CO2 concentrations.