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.