Effects of Elevated CO2 and N Addition on Growth and N2 Fixation of a Legume Subshrub (Caragana microphylla Lam.) in Temperate Grassland in China
Figure 4
The specific symbiotic nitrogenase activity (SNA, µmol C2H2 g−1 h−1) (A), and symbiotic nitrogenase activity per plant (PNA, µmol C2H2 g−1 h−1) (B) of C. microphylla.
Plants were grown under ambient (380 µmol mol−1) and elevated (760 µmol mol−1) atmospheric CO2 concentrations at two nitrogen levels (0 and 17.5 g N m−2 year−1) in 2008. Treatments: ambient CO2 without N addition (C); elevated CO2 without N addition (E); ambient CO2 with N addition (CN); elevated CO2 with N addition (EN). Bars represent means and error bars the standard error.