Quantitative comparison of freezing damage to detached Arabidopsis leaves determined either by chlorophyll fluorescence imaging (FV/FM; compare Fig. 1) or by electrolyte leakage measurements. Leaves for the freezing experiments were harvested from plants of the accessions C24 (upper panel) or Te (lower panel) either before (NA) or after cold acclimation (ACC). Error bars for electrolyte leakage data denote SEM from three to five replica. Chlorophyll fluorescence was measured on single samples. Measurements of chlorophyll fluorescence and electrolyte leakage were performed on parallel plants in the same experiments. The FV/FM axis has been inverted to allow for a more direct comparison between chlorophyll fluorescence and electrolyte leakage data.