Morphological and phytochemical screening of some Thymus ecotypes (Thymus spp.) native to Iran in order to select elite genotypes
Thymus spp. is one of the most important medicinal plants widely used in food, pharmaceutical, and cosmetic industries. In this research, different ecotypes of three Thymus species including T. daenensis, T. kotschyanus and T. lancifolius native to Iran were compared to two commercial cultivars of T. vulgaris (i.e. 'Varico 3' and 'Deutscher Winter') under identical conditions. Based on the results, there was a remarkable diversity among different ecotypes of Thymus species. The highest plant dry weight was found in T. daenensis (Malayer 2), T. kotschyanus (Azerbaijan gharbi), and T. lancifolius (Fars). The highest thymol percentage (>75%) was obtained by T. daenensis. The ecotype of Ilam belonging to T. daenensis gained highest essential oil percentage (7.83%). In all ecotypes of T. daenensis, thymol was the major constituent in their essential oil. Five chemotypes of citral, carvacrol-thymol, thymol-carvacrol, p-cymene-carvacrol, and geranyl acetate-citral were found in T. kotschyanus ecotypes, while four chemotypes of thymol, α-terpineol-linalool, carvacrol-thymol and thymol- geraniol were identified for T. lancifolius. In addition, in terms of growth, yield, and phytochemical traits, the elite genotypes within ecotypes were selected. Elite ecotypes and genotypes detected during this research could be used in Thymus breeding programs.