During the chilling–light treatment, PSII
photoinhibition was positive correlated to PSI photoinhibition in leaves, however, this correlation no
longer existed in leaves pretreated with DCMU, an inhibitor of electron transport from PSII to PSI.
Although the photoinhibitions of PSII and PSI in young leaves were more severe, the sensitivity of PSII
to excitation pressure was lower in young leaves.