Assessing Essential Oil Composition of Various Lamiaceae Accessions in View of Most Suitable Uses

Assessing the intra-specific variation in essential oil (EO) composition is the best premise for most suitable uses. In this frame, eight varieties of lavender (Lavandula officinalis), six genotypes of rosemary (Rosmarinus officinalis), and three genotypes of thyme (Thymus capitatus and T. cedrinus), grown at the same station in Northern Italy, were subjected to EO extraction (distillation) and analysis (gas chromatography/mass spectrometry). A wide range of EO yield was observed in lavender (from 0.42% to 1.07%), rosemary (from 0.10% to 0.89%), and thyme (from 0.03% to 0.11%). In lavender, several of the tested cultivars passed the AFNOR thresholds for either limonene, 1,8-cineole, camphor, linalool and linalyl acetate. However, this variation may be considered a resource more than a limitation, as a wider spectrum of potential uses can be addressed. In rosemary, main components also showing a relevant variation were α-pinene, 1,8-cineole and camphor, resulting in EO’s with different potential uses (from anti-bacterial to human health). Lastly, in thyme differences in thymol vs. geraniol and geranyl acetate between genotypes were remarkable, once more indicating potentially different uses. In the three herbs, EO constituents were also grouped in compound classes and expressed in terms of yields (i.e., EO yield × compound class content). This quantitative assessment of EO characteristics allows producers to choose the most suitable accession to grow, in order to enhance the amount of recoverable compounds. Lastly, a principal component analysis of EO constituents was proved able to reduce EO complexity, while retaining the fundamental information concerning genotype similarity/divergence.