The Effects of Soil Amendments and Bio-fertilizers Inoculation on Morphological Characteristics and Yield of Echium amoenum

Introduction: In recent years, the effect of ecological inputs on soil properties and plant growth characteristics has received renewed attention. Although the utilization of mineral fertilizers could be viewed as the best solution in plant productivity, this approach is often inefficient in the long-term in many ecosystems due to the limited ability of low-activity clay soils to retain nutrients. Intensive use of chemical fertilizers and pesticides in agricultural systems is also known to have irreversible effects on soil and water resources. Maintenance of soil fertility as a permanent bed for continuous production of agricultural products is one of the most important issues affecting the sustainability of food production. In order to achieve healthy food production, application of ecological inputs such as soil amendments and bio-fertilizers is inevitable. Humic substances are a group of heterogeneous molecules that are bonded together by weak forces; therefore, they have a high chemical stability. This material included 65 to 80 percent of total soil organic matter. Application of bio-fertilizers is an appropriate alternative of chemical fertilizers to enhance soil fertility. In fact, bio-fertilizers include different types of free living organisms that convert unavailable nutrients to available forms and enhance root development and better seed germination. Mycorrhiza arbuscular fungi are coexist microorganisms that improve soil fertility, nutrients cycling and agroecosystem health. Mycorrhizal fungi are the most abundant organisms in agricultural soils. Many researchers have pointed to the positive roles of mycorrhizal fungi on plants growth characteristics. Echium amoenum is a perennial plant belongs to Boraginaceae family. This plant is native of North of Iran. Petal extract of E. amoenum have sedative, diaphoretic, anti-inflammatory and anti-depressant effects. These plants are wild perennial herbs and known in Iran as oxtongue. It is one of the most important medicinal plants in Iranian traditional medicine. Petals of Iranian oxtongue have been advocated for a variety of effects such as demulcent, anti-inflammatory and analgesic, especially for common cold, anxiolytic, sedative and other psychiatric symptoms including obsession in folk medicine of Iran. Despite many research on the effects of organic acids and bio-fertilizers on different crops, there is scarce information on the effects of these factors for many medicinal plants. Therefore, in t