Essential oil yield and quality in rose-scented geranium: Variation among clones and plant parts

• Essential oil content higher in leaves than in leaves + stems.
• Negligible essential oil in stems.
• Essential oil composition in leaves differed from that in leaves + stems.
• Contents of free and total rhodinol varied with plant parts distilled and clones.

Rose-scented geranium (Pelargonium spp.) is an important aromatic plant whose essential oil is used in a variety of personal care products for imparting rose-like fragrance. It is obtained by distillation of fresh aerial biomass of rose-scented geranium cultivars. Although the essential oil is present mainly in the leaves, fresh aerial biomass consisting of both leaves and stems is distilled by farmers. Three clones of rose-scented geranium, viz., ‘Bourbon’, ‘Narmada’ and ‘LTC-2’, were evaluated for 10 morpho-economic traits and for the contents of 10 constituents in the essential oils of their leaves, and leaves + stems, to determine differences, if any, in the composition of their essential oils. The clones differed significantly for biomass yield, essential oil content, essential oil yield and for the contents of eight out of 10 studied essential oil constituents. Clone × plant part interactions were significant for contents of linalool, 10-epi-γ-eudesmol, free rhodinol (linalool + geraniol + citronellol) and total rhodinol (linalool + geraniol + citronellol + citronellol formate + geraniol formate) in the essential oil. The contents of ‘rhodinol’ (responsible for rose-like odour of geranium oil) were higher in essential oils of leaves + stems of ‘Bourbon’ but lower in ‘LTC-2’ than in their respective essential oils of their leaves. The contents of free and total ‘rhodinol’ were highest in ‘Narmada’ and, unlike in ‘Bourbon’ and ‘LTC-2’, were almost similar in essential oils of its leaves, and leaves + stems. The results suggested that the quality of the essential oil in rose-scented geranium may vary not only with clone but also with the composition of the biomass (in terms of plant parts) used for distillation. To the best of our knowledge, there is no report on genotype × plant part interaction for the content of essential oil constituents in aromatic plants.