Morphological, agricultural and chemical characterization of garden mint (Mentha spicata L.) clones and cultivars

This study aims to determine the morphological, agricultural, and chemical characteristics of Mentha spicata cultivars and clones under Isparta's ecological conditions. The field experiments were conducted during the vegetation periods of 2021 to 2022 using a randomized blocks design. The study investigated morphological and agricultural properties, along with content and composition of essential oil. The essential oil was distilled using the Clevenger apparatus, and its compositions were determined by GC-MS. The study resulted that the clones and cultivars exhibit characteristic morphological features of the species, including a short or absent petiole, a smooth, rugose (wrinkled), or slightly rugose (slightly wrinkled) leaf surface, and a spicate (spike-like) flowering state. The study found that the yields and essential oil ratios were higher in the summer cutting compared to the autumn cutting in both years. The total fresh herb yields were between 19.74-50.81 t/ha in the first year and 22.06-51.73 t/ha in the second year. Dry leaf yield, which is used as dried spice, varied between 2.93-6.73 t/ha and 3.14-5.66 t/ha for the respective years. The essential oil were between 0.4% and 3.2% during the studies. The cultivars Casablance and Spica-1 (second year) gave highest yields, whereas the highest essential oil ratio was obtained from Casablance (2.4%-3.0%) throughout the study. Carvone was the main component in 17 of the cultivars and clones. While the second component was limonene in 16 of them, 1.8 cineol was found in one (Spica-3). Except for carvone, five of the clones had piperitone oxide as the main component, and the other two were trans-piperitenone oxide or menthone/isomentone, respectively. In conclusion, Casablance cultivar and Spica-1 clone are suitable for cultivation due to their high yield and essential oil content and their compliance with codex and monograms in terms of essential oil content. In addition, other chemotypes for different sectors were selected for further studies.