Figure 2. Cold acclimation (CA) response in Solanum species. Plants at the mid-vegetative stage were exposed to an above-freezing temperature (2°C) for a maximum of 20 d after establishment at a control temperature (24°C) and then exposed to freezing (–3°C) for 30 min. Electrolyte leakage index (ELI) is the cellular electrolyte leakage ratio between cold-treated and control plants. An ELI = 1 indicates no significant leakage of electrolytes due to cold, while ELI >1 indicates significant leakage due to the treatment. Means (±SE, n = 4) are significantly different between CA and non-CA plants at P < 0.001 (***) or P < 0.01 (**).