The aim of this study is to elucidate the mechanism by which Zn deficiency
affects the physiological function and internal structure of apple leaves at various
Zn levels under field conditions. With this aim, we use pigment and photosynthesis
analyses as well as microstructure and ultrastructure observation to characterize
the physiological and structural changes induced in apple leaves by Zn deficiency
at latent and deficient levels. Chlorophyll fluorescence was also investigated to
better understand alterations of the photosynthetic center on chloroplast membranes
under different Zn deficiency conditions. This work presents detailed microscopic
evaluation of Zn deficiency in apple leaves and elucidates how progressive Zn
deficiency affects leaf structure and function.