Supplemental ultraviolet-B induced changes in essential oil composition and total phenolics of Acorus calamus L. (sweet flag).

The effect of supplemental UV-B radiation (sUV-B) was evaluated on the essential oil contents of sweet flag (Acorus calamus L.), a medicinal plant grown under natural field conditions. After the emergence of two leaves, plants were exposed to sUV-B radiation of 1.8 kJ m(-2) above the ambient level of UV-B. The level of essential oil and phenol contents increased with exposure to sUV-B. Exposure of sUV-B resulted in significant increase in p-cymene and carvacrol contents of essential oil. Decrease in the level of major component beta-asarone due to sUV-B treatment is of prime importance, because of its toxicological concern to human health.