Fig. 3

Phenotypic and physiological analyses of OP plants under low temperature treatment (4 °C) and after recovery at 25 °C. a Visible damage in the leaves of sweetpotato plants after 48 h cold stress treatment and 24 h recovery. b PSII photosynthetic efficiency (Fv/fm), c Ion leakage in detached leaves treated with 4 °C for 48 h, and d MDA contents in the leaves of WT and OP plants after 48 h cold stress treatment and 24 h recovery. Data are expressed as the mean ± SD of three replicates. Asterisks indicate significant differences between WT and OP plants by ANOVA at * p < 0.05 and ** p < 0.01