The effects of temperature on antioxidant activity, total phenolics and agronomic traits of two thyme species

Thyme plants are considered to be one of the most widely consumed herbs well-known for their essential oils and secondary metabolites. In order to evaluate the effects of temperature on antioxidant activity, total phenolics, agronomic traits and essential oil of two thyme species (i.e. Thymus vulgaris and Thymus caramanicus), a greenhouse experiment was conducted in 2015 with split plot in a completely randomized design with three replications. The results of this experiment showed significant differences between the two species and different temperatures in terms of the tr-aits measured. The essential oil percentage, antioxidant activity, total phenolics and plant height of Thymus carama-nicus proved to be more than those in Thymus vulgaris. The comparison of mean interaction effect for essential oil pe-rcentage showed that the value of this trait in Thymus caramanicus specimens treated with a temperature of 30°C was more than other treatments. The IC50 rates of Thymus vulgaris and Thymus caramanicus ranged from 24.37 to 54.43 µg/ml in different conditions and total phenolics ranged from 36.63 to 89.37 mg GAEg-1. In addition, the highest anti-oxidant activity, essential oil percentage and phenolic compounds were observed at a temperature of 30°C for both species.