The chlorophyll (Chl) and protein degradation during dark incubation of leaf discs was reduced by Sr2+, Ca^^, and spermine (Spm) treatments. Sr2+ inhibited most effectively the Chl degradation, which was remarkable 48 h after the treatment. The Chl degradation appeared in control discs within 24 h in the dark and Chl content decreased by about 50 % during 96 h. The proteins retained at least during 48 h of dark treatment in the presence of Sr2+, Ca2+, or Spm. The retardation effect of Sr2+, Ca2+ and Spm on the Chl loss and the disintegration of thylakoid membrane proteins may be due to a cationic protection of thylakoid membranes.