Figure 4.

Shoot net CO₂ evolution, net O₂ consumption, and RQ at night under ambient (390 µmol mol⁻¹) or elevated (720 µmol mol⁻¹) CO₂ atmosphere for three Arabidopsis genotypes and wheat receiving NO₃⁻ or NH₄⁺ (left). The effect was measured in the Arabidobsis wild type (wt), a transformant overexpressing nitrate reductase (NR overexpressor), and a double mutant lacking detectable NR activity (double mutant). Shown are the mean ± se (n = 6–14). Changes in the shoot RQ (ΔRQ) with the shift from NO₃⁻ to NH₄⁺ as an N source (right). For each parameter within one genotype, bars labeled with different letters differed by P < 0.10.