| Abstract
| - The chemical composition of the essential oils obtained from leaves and bracts of hydroponicallycultivated Origanum dictamnus L. (Cretan dittany), growing under various electrical conductivity (EC)levels (2.0, 4.0, and 6.0 mS/cm), was studied, using the nutrient film technique (NFT). The analysisof the essential oil content was achieved by GC-MS technique, and totals of 41 and 38 differentcompounds were identified in both cases of large-leaved and narrow-leaved samples of leaves andbracts, respectively. Differences in the composition content and of the percentage of each of theconstituents in the two studied samples (i.e., large-leaved and narrow-leaved) and within the essentialoils of leaves and bracts in both samples were observed. Carvacrol and p-cymene were identified asthe main constituents in all essential oils, whereas thymoquinone was found in higher percentage inthe essential oils of large-leaved than in narrow-leaved plants. The results obtained from GC-MSanalysis were submitted to chemometric analysis, and a phenotypic similarity of the essential oils ofnarrow-leaved O. dictamnus was observed, whereas the essential oils of large-leaved O. dictamnusshowed two separate subgroups Keywords: Origanum dictamnus essential oil; hydroponic cultivation; electrical conductivity; GC-MS
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