In light adapted leaves (for 15 min) steady state fluorescence yield (Fs´),maximal fluorescence (Fm´) after 0.8 s saturating white light pulse and minimal fluorescence(F0') were measured when actinic light was turned off and further calculation was made by using the equation F0' = F0/(Fv/Fm + F0/Fm') (Oxborough and Baker, 1997).