Investigating the effect of ecological factors on essential oil composition of medicinal species Stachys lavandulifolia Vahl. in Baghtilak rangeland of Sari.

According to the studies, environmental factors can affect the secondary metabolites in plants, including the essential oil and its chemical composition. therefore, it is essential to understand the effect of these factors and which of the environmental factors have a more effective role on the quantity and quality of secondary compounds extracted from plants. the purpose of this study is to investigate and compare the effect of physical and chemical properties of soil and climate factors including temperature and rainfall on the chemical composition of the essential oil of the medicinal species of Stachys lavandulifolia in the northern and southern aspects of Bagh tilak rangeland of Sari.

The present research was conducted in Baghtilak rangeland, which is one of the summer pastures of Mazandaran province. in order to take samples, plant samples were taken according to the patchy distribution of the plant in the region, the aerial branches of the plant were randomly collected in three selected spots with three repetitions from the northern and southern aspects in late June.then the soil samples were also collected at the base of the plant from a depth of 0-30 cm. after the samples were transferred to the laboratory, the essential oils of the plants were extracted by clevenger and their composition was determined by GC and GC/MS.  Soil samples were also measured and evaluated based on existing guidelines. also, the required meteorological information was obtained from the Kiyasar meteorological station. in order to analyze the quantitative and qualitative data of soil and essential oil, the normality of the data was first checked using the Kolmograph-Smirnov test. after confirming the normality of the data, using the independent T-student test, the comparison of plant chemical compositions and soil quality indicators in the two northern and southern spects was performed by SPSS version 22 software, and the relationship between the plant chemical composition data was analyzed. It was done with soil quality indicators and climatic data by PCA principal component analysis method in PC ord5 space.

The results showed that the yield of essential oil in the southern aspect is significantly higher (P≤0.05) than the northern aspect. Also, among the compounds obtained from the essential oil, the compounds α-Pinene, α-Fenchene, p-cymene, Sabinene, Thymol, α-Thujene, Limonene, GermacreneD, bicyclogermacrene, cis-sabinene hydrate with the highest amount have a significant difference from they showed themselves in two aspects. the data obtained from principal component analysis into main components in relation to soil and climatic factors with essential oil compounds indicate that soil chemical factors including EC, OM, Mg, MWD, bulk density, sand and silt have a stronger relationship compared to other factors. also, in this analysis, soil factors such as apparent specific gravity, pH, Ca, sand, and the climatic factor of temperature have a positive and direct relationship with Sabinene, β-Pinene, Myrcene, α-phellandrene, p-cymene, Limonene, cis-sabinene hydrate compounds, thymol, Germacrene D, bicyclogermacrene and Phytol. also, soil factors such as EC, OM, bulk density, silt, Cao, P, Na, SAR and precipitation climatic factor have a negative and inverse relationship with Cyclofenchene, 1-8-Cineole, cis-ocimene, α- Terpineol, Terpinene-4-acetate, Bicyclo, Caryophyllene and Hexadecanoic acid were established.

Conclusion :

The result of this research shows that the quantitative and qualitative performance of medicinal plants is affected by factors such as the type of species, climatic characteristics, soil characteristics and topographical conditions, and the effect of environmental factors on the components of secondary metabolites can be due to the different effects of these factors on The biosynthetic pathways of these compounds in the plant. also, the present study showed that the yield of essential oil obtained from the Stachys lavandulifolia plant in the southern aspect of Baghtilak rangeland is significantly higher than the northern aspect, so it is recommended to consider more for the exploitation of this aspect.