عنوان مقاله [English]
Introduction: The genus Arnica L. comprises of 32 species predominantly confined to the boreal and montane region of the northern hemisphere. Arnica species are rhizomatous perennial herbs belonging to the daisy family, with simple or branched stems bearing opposite leaves, and large, single or cymose heads of yellow flowers. A. chamissonis is distributed over North America from Alaska to New Mexico, and due to its low ecological demand it is easier to cultivate than A. montana. Arnica is a source of sesquiterpene lactones, flavonoids, essential oils, terpenoids, and phenolic acids and exhibits antiseptic, anti-inflammatory, antiradical, antibacterial, anti-sclerotic, antifungal, and antioxidant activities. The flower heads and other parts of the plant of two of the species have been used therapeutically: A. montana and A. chamissonis, both of them containing sesquiterpene lactones as pharmacologically active compounds. Arnica species are used in as many as 300 drug preparations in Europe and about 20 products in Canada. Moreover, A. chamissonisis a good source of bioactive compounds a valuable source of herbal raw material and a pharmaceutical substitute for the endangered mountain arnica. A. chamissonis extracts exhibit potent anti-inflammatory and anti-radical activity and possesses high antioxidant abilities that might be helpful in preventing or slowing the progress of free radical-dependent diseases. Low pH soil is one of the principal ecological requirements of Arnica. Good plant growth and flower yield was achieved on acid soils with a pH of 6.8 and below. After nitrogen, phosphorus and potassium, sulfur is considered as fourth major element in most crops. Rate of sulfur oxidation in soils vary and depend on population Thiobacillus bacteria in soil, particle size and environmental conditions.
Materials and Methods: This study was conducted as a complete randomized block design with three replications and four treatments including different levels of bentonite sulfur (0, 250, 500 and 750 kg/ha) combined with the bacterium Thibacillus thiooxidans. Traits such as height and width of plants, number of flowers on each plant, inflorescence diameter, fresh and dry yield of flowers in each plant per square meter and total phenols, total flavonoids, rutin, luteolin and apigenin content in flowers were measured. High-Performance Liquid Chromatography method (HPLC) was used to separate rutin, luteolin and apigenin. HPLC grade methanol and distilled water, each with 0.02% added TFT were used as solvents.
Results and Discussion: The results showed that A. chamissonis is compatible with Tehran’s climate and it can be cultivated in regions with a similar climate. The use of elemental sulfur has a significant role in reducing soil pH and soil pH decreased more rapidly with increasing sulfur. Thiobacillus bacteria by oxidation of sulfur produced some to sulfuric acid and at low buffered properties can considerably reduce pH. Different levels of sulfur fertilizer had a significant effect (P ≤0.01) on soil acidity (pH), electrical conductivity, and sulfur, iron, zinc and manganese levels. The use of 750 kg sulfur bentonite with Thiobacillus caused to reduce soil acidity by about 0.9 units, and it increased the electrical conductivity of the soil to 7.33 dS/m. The amount of soil sulfate as a result of oxidation of sulfur fertilizers increased linearly. The highest amounts of iron, zinc and manganese were measured in the treatment of 750 kg sulfur as 3.38, 3.84 and 27.94 mg /kg, respectively. In this study, supplying 250 kg of sulfur plus bio-sulfur caused to improve the morphological traits and the highest flower yield (20.67 g / plant) compared to control (3.66 g / plant). Also, it increased the amount of sulfur and micro-elements in the soil, but in the treatment of 500 and 750 kg sulfur per hectare due to increased electrical conductivity and soil salinity, the growth of Chamisso Arnica decreased. Therefore, these levels of sulfur are not suitable for this plant. Sulfur Bentonite is oxidized by Thiobacillus bacteria and other microorganisms and sulfuric acid is produced. Reducing acidity and, as a result, the release of stabilized and insoluble nutrients can increase their uptake capacity and improve plant growth and development. Due to the increased salinity and osmotic imbalance in the soil by the treatments of 500 and 750 g /kg sulfur, vegetation growth will be incomplete and plants quickly enter to the reproductive phase and produce fewer and smaller flowers. The highest content of rutin was measured in plants grown in soil treated with 750 Kg/ha sulfur while soil treatment with 500 Kg/ha sulfur resulted in highest content of luteolin and apigenin, both showing significant difference to the control.
Conclusion: Results of this study indicated that the Chamisso Arnica showed adaptability to the planting location and it can be mass-cultivated under similar conditions.