Effects of gibberellin on contents of photosynthetic pigments, proline, phenol and flavonoid in savory plants (Satureja hortensis L.) under salt stress

Salinity is one of the main obstacles to the successful growth and production of plants. Hormonal factors such as gibberellin as plant growth regulators can have different physiological and biochemical effects in plants under salt stress. In present research, the effects of different concentrations of sodium chloride (0, 30, 60, 90 and 120 mM NaCl) and gibberellin (0 and 100 µg L-1) on photosynthetic pigments, proline, malondialdehyde, phenol and flavonoid contents were studied. Results showed that with addition levels of salinity and application of gibberellin, rate of chlorophylls a and b also decreased. In the other hand, different concentrations of NaCl caused significant increase in contents of proline, phenol and flavonoid in comparison with control. In interaction of salinity and gibberellin also contents of these compounds increased significantly in comparison with control and individual treatments of NaCl. The accumulation of malondialdehyde that shows the rate of degradation and peroxidation of membrane lipids were significantly increased by salt treatments, while combined application of GA3 and NaCl caused reduction in malondialdehyde (MDA) content. These results showed that gibberellin can reduce negative effects on lipids peroxidation and thus increases the resistance of plants to salt stress conditions.