Introduction and Objective: Nutrition is an important factor in improving the quantity and quality of plant products, and the soil provides most of the nutrients plants require. In addition to nutrients, other factors, such as electrical conductivity, soil acidity and salinity, are important in soil fertility in any region. The genus Echinops belongs to the Asteraceae family, which usually grows in habitats with a lot of light, some humidity, subtropical areas and different types of soils. These plants are wild, and very important in terms of their chemistry a compounds. They have economic calues, medicinal uses, and application in the agricultural and medicinal industries. In this research, we investigated the effects of some environmental factors on secondary metabolites and antioxidant activity of Echinops kotschyi plant extract in three natural habitats in the west of Iran.

Material and Methods: The aerial parts of E. kotschyi, including inflorescence and shoot parts, as well as the soil around the roots of the plant were randomly collected from three stations; Eslamabad-e Gharb (Kermanshah province), and Manshet-Qalarang and Kabirkouh (Ilam province). For each station, information including station name, geographical coordinates, altitude above sea level, and other charasteristics was recorded. Powder was prepared from aerial parts of plant specimens after drying in the shade and at room temperature. After preparing a methanolic extract from the inflorescence and shoot parts, the Folin-Ciocalteu reagent and aluminium chloride were used to measure the total phenol and flavonoid contents of the extracts after preparing them as methanolic extracts. The antioxidant capacity was determined using the DPPH method. Soil samples were collected from the surface layer to a depth of 30 cm around the plant roots. The electrical conductivity of the soil was calculated using an EC meter, the acidity was measured using a pH meter, and the amount of plant nutrients was measured using aqua regia (mixture of HCl and HNO3). The statistical analysis was performed using the SPSS software package. A comparison of the data means was performed using Duncan’s multiple range test at a probability level of 5%.

Results: The results demonstrated that the lowest electrical conductivity of the soil was at Kabirkouh station (3.13 dS/m) and the highest value was at Manesht-Qalarang station (3.26 dS/m). Soil acidity (pH) varied between 7.28 at Kabirkouh station and 8.81 at Eslamabad-e Gharb station. The amount of phosphorus element in Kabirkouh station, valued at 8.55 ppm, was higher than that of Manesht-Qalarang and Eslamabad-e Gharb stations. Kabirkouh had more Calcium and Magnesium elements with values of 1301 and 98.1, which was higher than the two other stations. The highest amount of Sodium in the soil of Manesht-Qalarang was 11.69, while the lowest amount was 7.8 at Kabirkouh. The Kabirkouh station had the highest amount of Nitrogen (74 ppm). After that,  Eslamabad  station was located with a value of 56 and Manesht-Qalarang with a value 0f 53, respectively. The highest total phenolic and flavonoid content is related to the inflorescence part in the Kabirkouh station (1.31 ± 0.21 and 0.61 ± 0.12 mg/g DW, respectively) and the lowest content is found in the shoots of the Manesht-Qalarang station. There was a significant difference between the total phenolic and flavonoid extracts obtained from the shoot and inflorescence parts of the plant, as well as between the habitats of Kabirkouh and Eslamabad-e Gharb stations with Manshet-Qalarang station (P< 0.05). The lowest amount (0.21 mg/ml) of IC₅₀ (that is, the highest amount of antioxidant activity) is related to the flowering part of the plant from the Kabirkouh habitat. A lower antioxidant activity was indicated by the highest IC₅₀ value for the shoot part in the Manesht-Qalarang habitat, at 0.41 mg/mL.

Conclusion: Since plants are always exposed to environmental stress, they contain a variety of chemical compounds as antioxidants with defferent strucures and functions. The results showed that the inflorescence part of the plant in the Kabirkouh region has the highest amount of total phenol and flavonoids, and the highest antioxidant activity (with a lower IC₅₀ value). Kabirkouh's habitat may be more suitable for this plant due to its lower altitude, lower rainfall, and higher ambient temperature, compared to the other two habitats, habitat. The living environment and climate of different regions have a significant impact on the content of bioactive compounds and their activity. Environmetal and genetic factors affect the synthesis of secondary metabolites in plants, and it seems that genetic factors have a stronger affect than other factor. The Kabirkouh's habitat was less acidic in pH and conductivity than Manesht-Qalarang and Eslamabad's habitats. Kabirkoh habitat had more nutrients like calcium, phosphorus, magnesium, and nitrogen, while the Manshet-Qalarang habitat had more sodium. There is an inverse relationship between the synthesis of secondary metabolites and the amount of antioxidant activity with acidity, electrical conductivity, and the amount of sodium element, and there is a direct relationship between other nutrients. The amount of certain nutrients in the soil, such as phosphorus, calcium, nitrogen, and potassium, are factors in the production of secondary metabolites and plant active compounds, as well as the growth and development of  the plant. Moreover, soil pH or acidity is another important factor in the production of plant active compounds due to its effect on the absorption of soil nutrients.