Minimum and maximum fluorescence (F0, and Fm,respectively) of dark-adapted leaves were measured in the same leaves after 0.8 second for saturation pulse (35 W halogen lamp with 690 nm short pass filter) in previously dark-adapted samples.Variable fluorescence (Fv= Fm− F0) and maximum quantum yield of PSII (Fv/Fm) were calculated by the software of the Fluorometer,moreover maximal efficiency of the photochemical process in PSII(Fv/F0) was counted.