Figure 6.

The ratio of final plant N mass at elevated (70 Pa) to that at ambient (40 Pa) CO₂ partial pressure (A), and the ratio of final plant dry mass at elevated to that at ambient CO₂ partial pressure (B) plotted against the nodule mass ratio at elevated CO₂ partial pressure for the five leguminous tree species included in the study. Plants were grown in unfertilized soil at high water supply. The line in A represents a nonlinear regression equation: N_E/N_A = 0.80 + 0.038exp(0.060NMR), where NMR is nodule mass ratio. The line in B represents a similar equation: M_E/M_A = 0.88 + 0.047exp(0.062NMR).