In the present study the highest Fv/Fm values of young and old leaves were found with foliar FeSO4 application, which was attributed to higher chlorophyll a content in these plants (Redondo-GoLmez et al., 2007).
Bertamini et al. (2001) proved that the significant decrease in photosynthetic electron transport is mainly due to the loss of PSII activity in Fe-deficient grapevine leaves, and the loss of PSII activity is due to the loss of D1 protein and 33 kDa protein of the water-splitting complex.