Intermittent A/Ci curves show
adaptation of photosynthetic processes over time
Plants were exposed to each CO2 condition for an
extended period, and A /Ci responses were
determined every 2.5 h to assess any changes in photosynthetic
parameters (Fig. 1). After a 16-h day, plants were given an 8-h night
and then an hour to acclimate to the light before resuming
photosynthetic experiments. For all three conditions,Vcmax and J , as determined by the fitting
routine of Gregory et al. (2021), declined over the first day.
The decline in Vcmax and J was comparable
for the low CO2 and ambient CO2conditions but there was a much greater decline in the elevated
CO2 condition. Vcmax for the
elevated CO2 plants declined by 25% before the first
treated A /Ci and did not recover even
overnight. J for the elevated CO2 condition
recovered somewhat overnight but not entirely, indicative of some
persistent photoinhibition. The TPU capacity of the elevated
CO2 plants appeared to decline for the first day.