Aro et al. (1993) found that the photon flux density (PFD) to which leaves are adapted is important: pea plants acclimated at 65 ~mol photons m -2 s ~, compared with those acclimated at 700 p, mol photons m -2 s ~, undergo greater photoinhibition
when they are exposed to 1600 p~mol photons m 2 s