Agro-morphological and phytochemical studies of spearmint landraces (Mentha spicata L.) in Iran

Abstract

Spearmint (Mentha spicata L.) is one of the most important species of the Mentha genus, many of which are produced commercially on a large scale. Agro-morphological and phytochemical properties of 25 Iranian spearmint landraces were evaluated. The landraces were found to be significantly diverse phenotypically in terms of the following: plant height, main stem diameter, main stem length, number of lateral branches, number of leaves, length and width of fully grown leaves, length and width of inflorescence, fresh and dry weight, essential oil (EO) content and yield. The average dry weight yield, EO content, and yield of spearmint landraces were 520 g/m2, 1.12% (v/w), and 5.8 mL/m2, respectively. Overall, 40 constituents were recognized in the EOs, among which carvone (0.1–73.4%), menthone (0.1–62%), limonene (1.9–30.3%), neo-dihydro carveol (0.2–54.7%), pulegone (0.2–32.2%) and iso-menthone (0.03–26.3%) were the main components of all landraces, however, significant variation among them was detected. Among the tested landraces, Vardavard produced the highest content of EO, EO yield and indicated the highest carvone, respectively. Main stem length, fresh and dry weight yields significantly correlated with EO yield. Carvone showed a negative correlation with limonene. Morphological properties were not significant in terms of EO content and its constituents. In this research, it was obvious that the dendrogram differed more in morphological traits than phytochemical variables, which indicated the high potential of studied landraces for breeding programs.