ABSTRACT
PURPOSE: The current study investigated the effects of gamma irradiation on biochemical parameters and secondary metabolite accumulation in Summer Savory under field conditions. MATERIALS AND METHODS: The dry seeds of Summer Savory (with a moisture content of 12%) were exposed to gamma radiation at the doses of 20, 40, 60, 80, and 100 Gy. Non-irradiated seeds (0 Gy) were used as control. RESULTS: Our findings showed that gamma radiation at low doses (20-40 Gy) had no effect on biochemical parameters and secondary metabolites accumulation in S. hortensis. These parameters are steadily and significantly increased by raising gamma irradiation doses from 40 to 100 Gy. The highest amount of chlorophyll a and b, carotenoids, anthocyanin, and total phenolic and flavonoid content were observed in 80 and 100 Gy treatments. Plants exposed to 80 and 100 Gy treatments accumulated the maximum amounts of rosmarinic acid and caffeic acid, respectively. Furthermore, the analysis of S. hortensis essential oil revealed that gamma radiation significantly alters its components. Carvacrol, α-Pinene, and α-Thujene levels raised dramatically compared to control with an increase in gamma irradiation dose from 20 to 100 Gy, while Thymol and α-Terpinene levels lowered. CONCLUSIONS: Our results showed that treatment of Summer Savory seeds with gamma radiation at 80 and 100 Gy doses could significantly be raised biochemical parameters and secondary metabolites accumulation under field conditions. The current study showed that gamma irradiation could be used as a pre-sowing elicitor to improve the quantity and quality of phytochemicals in Summer Savory.
