Appendix A. A figure showing ΔAQ, the decrease in the ratio of shoot CO2 consumption to O2 evolution with a shift from NH4+ to NO3– nutrition, as a function of shoot internal CO2 concentration (Ci) for two C3 grass species, two C3 herbaceous dicotyledonous species, two C3 coniferous species, two C3 dicotyledonous tree species, two C3-C4 intermediate species, and three C4 species.