Physiological and biochemical responses of Hypericum perforatum to salt stress and salicylic acid spraying

Salinity is one of the main obstacles to the successful production of agricultural products. Hormonal compounds such as salicylic acid (SA) 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 (2, 6 and 10 dS/m) and foliar application of SA (0, 0.25 and 0.5 mM) on leaf relative water content, proline, anthocyanin, phenol and flavonoid contents, and dry matter of root and shoot were studied in completely randomized design. When the plants were 10 cm in height, foliar application was done 2 times by 7 day interval and then salinity treatments were initiated. Results showed that salinity treatments reduced leaf relative water content and shoot and root dry matter, while salicylic acid application increased these traits under salinity stress. Foliar application of salicylic acid increased leaf proline and anthocyanin content, especially at 6 dS/m salinity. Severe salinity and salicylic acid at 0.25 mM increased leaf and root phenol content by 13 and 17%, respectively. The highest increase in leaf and root flavonoid was 66% and 89% under severe salinity stress with application of 0.5 mM salicylic acid. Overall, the results of this study showed that with application of 0.25 mM of salicylic acid can reduce the negative effects of salinity stress, especially at 6 dS/m salinity level in Hypericum perforatum and also increase the resistance of this plant. resistance of this plant.