Effects of fertilizer on yield, essential oil composition, total phenolic content and antioxidant activity in Satureja hortensis L. (Lamiaceae) cultivated in Iran

The effects of different amounts of compelet fertilizer on the yield, fresh and dry weight, essential oil composition, total phenolic content and antioxidant activity of Satureja hortensis L. was investigated. Different amounts of compelet fertilizer (0, 500, 1000 and 1500 mg/plant) were applied. The results showed that the use of fertilizer increases fresh and dry weigh in S. hortensis. One thousand and five hundred mg/plant compelet fertilizer enhanced the essential oil yield and essential oil efficiency. Nineteen components were identified in the essential oil of S. hortensis underwent at different treatments, that represented 97.58 - 99.24% of the oils. The major components were carvacrol (43.9 - 59.2%), gamma-terpinene (30.7 - 40.2%), alpha-terpinene (2.8 - 4%) and P-cymene (1.8 - 2.2%). The effect of different amounts of fertilizer on the essential oil composition was very slight and was not significant. But the amount of some component such as carvacrol, gamma-terpinene and alpha-terpinene was changed with using of fertilizer. Total phenolics and antioxidant activity of plant extracts were measured by the Folin-Ciocalteu and DPPH free radical scavenging assays, respectively. The total phenolic content varied from 23.58 to 24.52 (mg gallic acid equivalent/g dw) and the highest value was found in 1000 mg/plant compelet fertilizer treatment. IC50 values in the DPPH assay ranged from 8.45 to 8.6 mu g/ml and the highest activity was observed in 1000 mg/plant compelet fertilizer treatment. The use of fertilizer increased total phenolic content and antioxidant activity in S. hortensis. Also, We have found a positive correlation between the total phenolic content and antioxidant activity in S. hortensis (R-2 = 0.55).