Investigating the effect of topography and soil factors on some quantitative and qualitative characteristics of Astragalus parrowianus Fischer. gum tragacanth (Case study: Jalambadan Rangelands, Jovein)

This study was carried out with the aim of investigating and knowing the chemical and physical characteristics of Astragalus parrowianus Fischer and the relationship of these characteristics with soil and topographical characteristics in Jalamabadan rangeland of Joveyn city. At first, the studied area was divided into four places where A. parrowianus was present for sampling. In July and August of 2019, the study area was visited to take samples of tragacanth and then by using of scientific resources and the guidance of local operators, 4 different sites with the presence of A. parrowianus were identified. Then, in each of the places, the tragacanth was extracted from the plant bases and A profile was dug at a depth of 0-60 cm in order to prepare a soil sample. Quantitative characteristics of tragacanth, including production, ash, viscosity, and qualitative characteristics of Tragacanth, including potassium, calcium, phosphorus, and sodium elements, arabinose, galactose, fructose, glucose, sucrose sugars, and proline, serine, and valine amino acids were measured. In the collected soil samples, the factors of electrical conductivity, percentage of sand, silt, clay, pH, soil water saturation percentage, potassium and organic matter were determined in the laboratory using standard methods. Also slope, aspect and elevation maps were prepared in order to determine the topographic characteristics. Then, using one-way analysis of variance, the difference between the sites was investigated in terms of quantitative and qualitative characteristics of tragacanth and soil characteristics. Finally, using the Redundancy Analysis (RDA), the relationship between the environmental characteristics and the characteristics of tragacanth was investigated. Among the soil characteristics, the amount of organic matter, the percentage of clay, sand, the amount of gravel and electrical conductivity have significant differences in the studied sites. While potassium, pH and percentage of silt have no significant difference among the studied sites. Except for valine, magnesium, sucrose and galactose, the physical and chemical characteristics of tragacanth have significant differences among the investigated sites. Site 1 has the lowest amount of viscosity, calcium, sodium, fructose, proline and the highest amount of product and ash. Site two has the highest amount of potassium, phosphorus, arabinose, glucose, and proline. The third site has the highest viscosity, calcium and serine and the lowest sucrose and galactose. Site four has the lowest amount of ketira, potassium, phosphorus, arabinose, glucose, ash, serine and the highest amount of sodium and fructose. Also, about 90% of the changes are justified by the first axis of the RDA diagram and the variables of height above sea level (72%), soil alkalinity (42%), slope direction (36%), electrical conductivity (34%) and slope percentage (33%) were the most important effective factors in differentiating the different growth locations of A. parrowianus in Jalmabadan region. According to the results, the characteristics of tragacanth gum are influenced by environmental factors, and each of the characteristics of tragacanth gum are affected by certain environmental characteristics. From this, for various industrial purposes that certain characteristic of Katira gum is important, it is necessary that the effected environment in which the species grows or its gum is harvested should be in optimal conditions.