Brassinosteroids Promote Growth and Secondary Metabolite Production in Lavandin (Lavandula intermediaEmeric ex Loisel.)

Lavandin (Lavandula x intermedia), a hybrid between L. angustifolia (English lavender) and L. latifolia (spike lavender), is a valuable aromatic and medicinal plant cultivated in the world. Lavandin essential oil with characteristic scent and fragrance properties is mainly used in cosmetics, perfumes and pharmaceutical industries. The objective of this study was to determine the effect of foliar application of 24-epibrassinolide (24-eBL), a brassinosteroid analogue, on growth and secondary metabolite production of lavandin (Lavandula x intermedia var. Super). 24-eBL at 0, 0.75, 1.5 and 2.25 mg/L concentrations was applied to 8 years old plants twice. The highest growth parameters were obtained from the plants applied with 1.5 and 2.25 mg/L of 24-eBL. 24-eBL also increased the total phenolics and essential oil contents. Especially 1.5 mg/L 24-eBL application was the most suitable concentration for total phenolic and essential oil contents. Besides 24-eBL also modified essential oil composition. The percentages of linalyl acetate and 1,8-cineol increased while some of the components such as camphor, borneol, geraniol and lavandulyl acetate decreased with the 24-eBL applications. To conclude, 24-eBL may be a promising compound for use in lavandin cultivation because of its positive effects on plant growth, phenolic content, essential oil content and oil quality.