The Effect of Salinity Stress on Chemical Compounds of the1 Essential Oil of Mentha piperita L.

Mentha piperita L. is one of the most commonly used medicinal plants. Given that environmental stresses, such as salinity stress, can affect the production of secondary metabolites, this research was carried out to evaluate the impact of salinity stress on the quantity and quality of peppermint essential oil composition in a randomized complete design with three replications at four levels of salinity including 0, 75, 150 and 200 mM sodium chloride in the greenhouse of the Islamic Azad University, Yadegr-e Emam branch. The essential oil was extracted using Clevenger's apparatus and GC/MS was used for the identification of essential oil composition. Totally, 22 compounds were identified for all treatments, of which 16 compounds belonged to the control treatment. In the stresses of 75, 150 and 200 mM, 17, 17 and 18 compounds were identified, respectively. In all treatments, the three main compounds were menthol, Mentone and neo-menthol. The highest amount of menthol was found in 75 mM sodium chloride treatment. The amount of neo-menthol in 0 and 75 mM treatments was almost equal, but there was a difference between 150 and 200mM treatments in this regard. Generally speaking, the results of this experiment revealed that that the main components of peppermint essential oil are affected by salinity stress. That is, with a 75 mM increase in salinity level the two main compounds of Menthol and Mentone increase, but increasing it up to 150 and 200 mM decreases them. The minor components of the essence such as 1 and 8-Cineole, limonene and caryophyllene decrease with an increase in salinity level in all treatments.