Effects of salicylic acid and selenium foliar application on salinity tolerance and essential oil yield of moldavian balm (Dracocephalum moldavica L.)

Salicylic acid (SA) and selenium (Se) are compounds with antioxidant properties that cause improved plant growth under stress condition. In order to investigate the effects of salicylic acid and selenium application on some vegetative and reproductive traits, essential oil yield, and potassium to sodium ratio in roots and shoots of moldavian balm (Dracocephalum moldavica L.) under salinity stress conditions, an experiment was carried out as a factorial based on a completely randomized design with three replications in the green house of Agricultural and Natural Resources Research Center of Qom, Iran, 2015. The experimental treatments comprised three Se levels including 0, 20 and 40 mg/L, two SA levels including 0 and 0.5 mM and two salinity levels including 0 and 100mM NaCl. Results showed that salinity stress decreased the number of active leaves per plant and plant height. Salinity stress increased the number of flower per plant and essential oil yield. Results showed that, under salinity stress conditions, the application of Se and SA both alone or combined decreased the negative effect of salinity stress on the number of active leaves per plant and plant height, while increased the essential oil yield. Moreover, the foliar application of Se combined with SA increased the potassium to sodium ratio of leaves under salinity stress. In general, it could be stated that the foliar application of Se combined with SA could be used to relieve the effect of salinity stress in Moldavian balm.