Effects of growth-light quantity, growth-light quality and CO2 concentration on Rubisco deactivation during low PFD or darkness

Abstract

The effects of CO2 concentration and the effects of growth-light conditions on Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) deactivation were examined for Spinacea oleracea (spinach). Rubisco deactivation kinetics and the degree that Rubisco activation limited the rise in photosynthesis following an increase in photon flux density (PFD) were determined from gas-exchange time courses. There were no significant differences in the apparent relaxation time for Rubisco deactivation among leaves exposed to high or low CO2 (50 or 1000 μmol mol-1) and low PFD (170 μmol m-2 s2+) or darkness. However, when PFD was increased to 1700 μmol m-2 s-1 following a period of low PFD or darkness, l..