Effects of salicylic acid on physiological traits of myrtle seedlings in salt stress condition

Salicylic acid is known as an important signaling molecule that regulates plant reactions to environmental stresses. It plays a critical role in the regulation of physiological functions as non-enzymatic antioxidant. In this study we investigated the effects of different concentrations of salicylic acid (0, 50, 100 and 150 ppm) that were sprayed on one age seedlings of myrtle (Myrtus communis L.) with different levels of NaCl (0, 25, 50, and 100 mM) on activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), catalase (CAT), glycinebetaine (GB), proline, hydrogen peroxide (H2O2) and ionic leakage (ELI). Interactions of salicylic acid at 50 ppm with 50 mM salinity showed significantly increase in the CAT activity. GPX and APX were significantly higher in 50 mM salinity level with 50 and 100 ppm salicylic acid concentrations. The highest activity of SOD was observed in 50 mM of salt and 50 ppm of salicylic acid, indicated that 50 ppm had highest resistance against salt concentration. Proline in 50 mM salinity with 50 ppm salicylic acid showed the most significant increase in the 100 mM of salinity had a sharp decline in their interactions. GB had maximum amount in 25 mM salinity with all of salicylic acid treatments. Ionic leakage had significant interactions but was not significant with increasing salinity and salicylic acid treatments. The hydrogen peroxide showed the most significant increase in 100 mM salinity with 100 and 150 ppm salicylic acid levels respectively, and effectiveness of their interaction in 100 mM of salt with all treatments of salicylic acid except control.