Evaluation of changes in oil cells and composition of essential oil in lemongrass (Cymbopogon citratus (D.C.) Stapf.) due to supplemental ultraviolet-B irradiation.

Field grown lemongrass (Cymbopogon citratus (D.C.) Stapf.) was exposed for a short duration (3 h/day) to supplemental ultraviolet-B (sUV-B) to evaluate its effect on oil cells and chemical composition of essential oils. Histochemical studies showed an increase in number of oil cells in tissues under sUV-B treatment. Estimation of essential oil content also demonstrated an increase of 25.7% in sUV-B treated plants over its control. Gas chromatography-mass spectrometric (GC/MS) analysis of essential oils demonstrated significant variations in qualitative and quantitative expression of oil constituents of sUV-B exposed plants. sUV-B irradiation induced the formation of major compound z-citral within the investigated oil samples by 117.56% as compared to oil obtained from nonirradiated plants. Geraniol formate, pulegol, linalyl formate and other compounds also showed significant variations after sUV-B treatment. Results suggest that sUV-B exposure stimulated the production of oil cells vis-a-vis positive change in quality and percentage of essential oil contents of lemongrass. The results suggest some future prospects for better economical utilization of lemongrass after irradiation with low doses of sUV-B for its commercial exploitation.