| چکیده انگلیسی مقاله |
Background and objectives: In different ecosystems, factors such as altitude, rainfall, temperature, lighting, humidity, and soil nutrients are essential variables that affect the metabolism and accumulation of secondary metabolites. Therefore, it is vital to know the factors affecting the active substances of medicinal plants. Therefore, researchers try to increase the production of effective substances by different methods. We can mention the research conducted in the field of the effect of ecological factors on the essential oil compounds of different populations of Nepeta crispa, Salvia sharifii, Satureja rechingeri and Stachys pilifera. This study investigated the relationship between climatic, topographical, and edaphic parameters as necessary factors that influence the morphological traits and essential oil compounds of the medicinal endemic species Dracocephalum ghahremanii Jamzad. Methodology: Three habitats of D. ghahremanii were selected in Semnan province with different environmental conditions, and 15 plots of 4 m2 were established by systematic random method. In each plot, the plant height, canopy diameter, cover, biomass and leaf area of the studied species were measured. Flowering branches were collected from natural habitats with three replications, and essential oils were extracted using a hydrodistillation method using a Clevenger apparatus. GC-FID and GC/MS identified the essential oil compounds. Five soil samples were randomly taken from inside the plots in each habitat, and some soil physicochemical parameters, including pH, EC, OM, N, P, K, lime and soil texture, were measured. Analysis of variance and comparison of data mean was done using SPSS software. The most important environmental factors affecting morphological traits and essential oil compounds were determined using the correlation analysis method in SPSS software and the principal component analysis (PCA) method in Minitab software. The conservation status of this species was determined using the IUCN method and based on the criteria of EOO and AOO using GeoCAT software, as well as data related to population size and habitat quality. Results: Comparing the average morphological traits of D. ghahremanii showed that the highest and lowest values of morphological traits are related to the Tash region with an altitude of 3043 meters and Tang Kavard with an altitude of 2032 meters, respectively. Variance analysis of morphological traits also showed a significant difference between the plants of the three regions in terms of leaf area at the level of 1% and in terms of plant height, canopy diameter, canopy cover and biomass at the level of 5%. The analysis of D. ghahremanii essential oil showed that its chemical composition differs in three regions. In Tang Kavard region, (E)-β-Farnesene, trans-Cadina-1(6),4-diene and (E)-Caryophyllene, in Dibaj region,(E)-β-Farnesene, trans-Cadina-1(6),4-diene and Caryophyllene oxide, and Tash region, Caryophyllene oxide, α-Vetivone and Carvone hydrate were identified as dominant compounds. Analysis of the variance of common essential oil compounds of this species also showed a significant difference between the averages of these compounds at 0.1%. Physicochemical parameters of D. ghahremanii habitats had significant differences. Variance analysis of the values of these parameters showed that there is a significant difference between the three regions in terms of OM, N, P, K, lime, sand and silt at the level of 0.1%, pH at the level of 1% and EC and clay at the level of 5%. Correlation between the characteristics of this species with some environmental factors showed that altitude, annual precipitation, annual temperature, minimum temperature of the coldest month, maximum temperature of the hottest month, lime, OM, N, P, sand and silt have the most significant correlation with morphological characteristics and essential oil compounds. Considering that the area occupied by this species in the studied populations (AOO) is 0.750 km2 and its presence area in the province (EOO) is 691.046 km2, its conservation status in Iran was determined as Critically Endangered (CR). Conclusion: As a general conclusion, the increase in altitude has increased the functional characteristics (morphology and phytochemistry) of D. ghahremanii. Despite the relative similarity of the dominant compounds in the essential oil of this species, the composition of the essential oil (percentage of major and minor components) was different in the three investigated regions. Among the environmental parameters, altitude, annual precipitation, OM, N, P, K and silt were the most critical factors affecting the morphological traits and the percentage of oxygenated terpenes, which can indicate the importance of high altitude habitats in terms of essential oil content and compounds with higher antioxidant properties for this plant. Based on these findings, the maximum temperature of the hottest month, the minimum temperature of the coldest month, and the absolute minimum temperature of lime and sand were the most important parameters affecting the percentage of hydrocarbon terpenes. These results can be significant for extracting D. ghahremanii essential oil from natural habitats or commercially cultivating this plant to extract the secondary compounds in its essential oil. |