Abstract

Medicinal plants play a key role in the human health and have a huge share in the global economy. Cultivation of Salvia species is increasing mainly due to high commercial worth of this plant in food, medicine, perfumery, and cosmetic industries. The aims of this research were: (1) to determine drought tolerant Salvia spp. and (2) examining drought stress effects on germination and seedling growth, separately. Seeds of 36 Salviaaccessions (15 species) collected from different regions of Iran were primarily treated by soaking and gibberellic acid was used to break the seed dormancy. Afterwards, germination rate, percentage and early seedling growth were measured in two separate tests with four osmotic potentials: 0 (control), -0.3, -0.6, and -0.9 MPa using polyethylene glycol (PEG, 6000). The principal-component analysis (PCA) summarized all traits into two components ("germination" and "seedling growth") in all osmotic treatments. There was significant correlation between germination traits and among seedling growth traits in -0.3 and -0.6 MPa, but correlation between the traits of two components was not significant. Tolerance of genotypes to drought stress in germination and seedling stage showed a high diversity. Tolerant accessions for both components are suitable for cultivation in controlled conditions, but tolerant accessions only for "seedling growth" component, probably would be appropriate for distribution in their habitats for conservation purposes. However, the accessions which simply germinate at water stress conditions, but are susceptible at seedling stage, will die and lose their seed bank in the soil.

Key words: Germination, medicinal plant, osmotic stress, polyethylene glycol (PEG), Salvia, seedling growth.