Effects of Glycerol and Salicylic Acid on Freezing Tolerance of Iranian Petunia (Petunia hybrida L.)

The aim of this study was to investigate the effects of glycerol (GL) and salicylic acid (SA) on freezing tolerance of Iranian Petunia (Petunia hybrida). For this purpose, a factorial experiment based on completely randomized design with three replications was conducted under controlled conditions. The first factor was temperature (0 and -4 °C) and the second factor was spraying with anti-stress compounds (24 hours prior to freezing) consisting of control (distilled water), salicylic acid (75 and 150 mg per liter), glycerol (0.1, 0.25, 0.5 and 1 percent) and the combined treatment of 150 mg/l SA+ 0.25% GL, 150 mg/l SA+ 0.5% GL, 200 mg/l SA+ 0.25% GL and anti-frost trade agent with concentration of 4 percent. The results of this study showed that under freezing stress conditions, SA and GL reduced the percentage of visual damage and electrolyte leakage and increased concentration of proline, and total carbohydrates, total phenols and antioxidant activity as compared to control plants. The percentage of visual damage in plants treated with 150 mg/l of SA + 0.5% GL at -4 °C was 3.33%, while the percentage of visual damage of control plants and those treated with anti-frost trade agent were 57.61 and 22.88 percent, respectively. The highest proline concentration was obtained from application of 150 mg/l of SA + 0.25% GL at -4 °C temperature. The results of this study showed that the use of SA and GL reduced the freezing-induced damage in Iranian Petunia through the improvement of physiological indices.