The abaxial sides of leaf discs (1 cm2) were floated on the surface
of water at 6 C. The temperature of water was controlled by
RTE-211 water circulator (Thermo, USA). For photoinhibition treatments,
400 lmol m2 s1 light from red and blue (8:1) light emitting
diode (LED; Senpro, China) was used.