Figure 2.

The rate of isoprene emission in hybrid aspen leaves is dependent on the in vivo DMADP pool size measured at 28°C to 30°C. The DMADP pool size was calculated as the integral of the postillumination isoprene emission (see Fig. 1 for sample postillumination isoprene emission kinetics) for different combinations of environmental conditions before terminating the illumination. The standard conditions in the experiments were 21% O₂, 390 μmol mol⁻¹ CO₂, and incident quantum flux density of 550 μmol m⁻² s⁻¹. In experiments with varying CO₂ (black symbols), CO₂ concentration was increased from 390 μmol mol⁻¹ (highest emission rate for the given treatment) to 1,600 μmol mol⁻¹ (lowest emission rate). In experiments with varying light, light was reduced from 550 to 150 μmol m⁻² s⁻¹ (lowest emission rate observed for the given treatment). In all individual experiments (n = 17), steady-state isoprene emission rates at specific cuvette conditions were established before measuring the decay kinetics.