Figure 6.

Electrochromic shift kinetics measured using MultispeQ. (a) Detector and LED set-up to measure the electrochromic shift. (b) Measurements were done as before with a healthy leaf using ambient air (about 400 ppm CO₂) and flushing the MultispeQ device with CO₂-free air containing 99% N₂ and 1% O₂. During the measurement with the mixed gas, the dark period was increased to 900 ms to account for the slower decay. (c) Absorbance change over time on Glycine max. leaves at three different developmental stages, the oldest trifoliate, a young but full expanded leaf, and an immature (sink) leaf. Leaves were adapted for 10 min at a light intensity of 300 µmol photons m⁻² s⁻¹. The actinic background light was turned off after 300 ms and turned back on again after 300 ms. The data represent the average of 15 traces taken at 4.5 s intervals.