عنوان مقاله [English]
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 this study effect of organic acids and bio-fertilizers on morphological characteristics and yield of Echium amoenum in a low input cropping system was studied.
Materials and methods: In order to evaluate the effects of soil amendments and different bio-fertilizers on morphological characteristics and seed yield of Echium amoenum, an experiment was conducted based on randomized complete block design with three replications during 2011-2013 growing seasons, at the Research Farm of Ferdowsi University of Mashhad, Iran. Treatments were eight different types of soil amendments and bio-fertilizers concluding: 1) Humic acid, 2) Fulvic acid, 3) Nitroxin® (Azotobacter spp. and Azospirillum spp.), 4) Biophosphorous® (Bacillus sp. and Pseudomonas sp.), 5) Biosulfur® (Thiobacillus spp.), 6) Mycorrhiza (Glomus mosseae), 7) Mycorrhiza (Glomus intraradices), and 8) no fertilizer as control.
Result and Discussion: The results showed that mycorrhiza species increased flower yield compared with control, as the flower yield in treatments of G. mosseae and G. intraradices were 24 and 11 percent more than control, respectively. Soil amendments and different bio-fertilizers increased the number of flower cycle per plant compared with control. Although the effect of biophosphorous® was more pronounced, as the number of flower cycle per plant increased from 342 to 1322 cycles in control and biophosphorous® , respectively. Humic acid treatment increased seed yield, biological yield, seed weight and seed number per plant by 82, 66, 63 and 66 percent compared with control, respectively. It seems that different species of mycorrhiza improved morphological characteristics and yield of Echium amoenum, because of better conditions to absorption and transportation of nutrient to the plant. It has been reported that organic acids provide favorable conditions for plant growth and development through improvement of physical, chemical and biological properties of the soil. Therefore, it could be concluded that improvement of most studied traits in the present study was as a result of use of organic acids.
Conclusions: Generally, our results showed that organic acids and biological fertilizers had positive effects on most of studied criteria. The highest flower and seed yields were obtained from G. mosseae and Humic acid treatments, respectively.