effects of exogenous salicylic acid application on growth, metabolic activities and essential oil composition of satureja khuzistanica jamzad

background: satureja khuzistanica jamzad, with the common persian name “marzeh khuzestani”, is an endemic medicinal plant, distributed in the southwestern areas of iran. salicylic acid (sa) is a signaling molecule and a hormone-like substance that plays an important role in the plant physiological processes. objective: this study was conducted to determine the influence of foliar sa application (0, 50, 100, 200 and 400 mg.l-1) at two times including vegetative stage (vs) and both vegetative and reproductive stages (vs+rs) on growth parameters, enzymes activity including superoxide dismutase (sod) and polyphenol oxidase (ppo), prptein content, essential oil percentage and composition of s. khuzistanica under field conditions. methods: the essential oils were isolated from aerial flowering parts of the plants by hydro-distillation method and then subjected to gc and gc-ms analyses to determine the oil constituents. results: results showed that sa application at 100 and 200 mg.l-1 were the most effective treatments in growth characteristics, but the highest essential oil content and yield was obtained at 400 mg.l-1 sa treatment. in both spraying times, plants treated with 100 and 200 mg.l-1 sa concentration showed more ppo and sod activity than control plants, respectively. also, results showed that the 14 compositions were identified in essential oil of plants under all employed treatments. carvacrol was the major component of oils, which is also showed more variability than that of other components. conclusion: it was concluded that foliar spray of sa at low concentration once at vegetative and second time at reproductive stage might be employed for enhancing both primary and secondary metabolites production of s. khuzistanica plants.