Figure 5

Endogenous melatonin (a) and ABA (b) concentration in leaves of DX and GN under cold stress. The 21-day-old seedlings were pretreated with distilled water, 50 μM melatonin, 100 μM ABA, 50 μM fluridone, and 50 μM melatonin + 50 μM fluridone (MET + F) for 7 days, respectively, and then exposed to cold stress (4 °C). Samples were taken at 0, 1, 3, 6, 12, 24, and 120 h of cold treatment. Untreated controls were taken at time zero after the experiment began. Each value represents the mean of three replicates ± SD, and different letters above the bars indicate significant differences at P < 0.05 among different time points in the same genotype according to Duncan’s multiple range test.