The effect of foliar application of chitosan on yield and essential oil of savory (Saturejaisophylla L.) under salt stress

Satureja Isophylla L.  is a medicinal herb which belongs to the family Lamiacease. Salinity affects the growth, the quality and quantity of essential oils of medicinal plants. Chitosan is also considered as a biological elicitor which plays a role in improving production of secondary metabolites of medicinal herbs. The current project was conducted to evaluate the effect of different concentrations of chitosan on growth indices and the quality and quantity of essential oil under salt stress (salinity). In this study, savory was treated by chitosan at three levels (0, 0.2 and 0.4 g/l) and NaCl with three concentrations (0, 50, and 100mM). After a two-week treatment, the dry weight of the root and the stem, the herb height, and the number of leaves and lateral branches were measured. In addition, the composition of the herb's essential oil was analyzed and identified by GC/MS. The results showed that salt stress decreased the dry weight of the root and stem, the herb height, and its number of leaves and lateral stems. Chitosan treatment could amend this reduction. Sodium chloride mutual treatment with the concentration of 50 mM as well as that of chitosan with the concentration of 0.2 g/l had a significant effect on the increase of the yield and quality of the essential oil. The results of the GC/MS analysis showed that 14 main compositions were detected in the essential oil, in which the major amount belonged to P-Cymene (3.13%), Y-Terpinene (28.97%) and Caryacrol ( 59.64%). The findings indicated that the utmost amount of Carvacrol was obtained by the increment of salt stress at the salt concentration of 100 mM and with chitosan concentration of 0.4 g/l; moreover, the greatest amount of P-Cymene and Y-Terpinene was obtained by the increment of salt stress with salt concentration of 50 mM and chitosan concentration of 0.4 g/l. Chitosan is recommended to be exploited in industry as it has moderating effects against salt stress in addition of the increment influence on the certain secondary metabolites of savory.