مجله زیست شناسی خاک
سال دوازدهم شماره 1 (بهار و تابستان 1403)

In recent years, the efficiency of native and compatible isolates of fluorescent pseudomonads in promoting the growth of various medicinal plants has been noticed. Fluorescent pseudomonads are a group of bacteria belonging to the genus Pseudomonas that produce a fluorescent green siderophore called pyoverdine under iron-deficiency conditions. These bacteria may also naturally enhance plant growth through other mechanisms such as fixing atmospheric nitrogen, synthesizing plant hormones, solubilizing phosphate, and suppressing plant pathogens and pests. Among the native medicinal plants of Iran, Reshingari savory (Satureja rechingeri Jamzad.) as a critically endangered species is of great importance. This species is utilized in traditional medicine as an antioxidant, digestion facilitator, anti-inflammatory, diuretic, sedative, and disinfectant, as well as in teas and spices. In this way, it is necessary to attempt to domesticate, promote cultivation, and enhance the growth of Reshingari savory using eco-friendly methods. The purpose of this study was to identify the most effective native and compatible isolates of fluorescent pseudomonads in terms of producing the pyoverdine siderophore. Additionally, the present study aimed to investigate the stimulating effects of these isolates on the growth parameters of Reschingari savory under field conditions.

In this study, sampling was performed randomly from the depth of 25 cm of Satureja rechingeri roots and rhizospheric soil in the natural habitats of Mehran County in Ilam Province, Iran (n=3). Screening of the fluorescent pseudomonads’ isolates were conducted based on the production of fluorescent green pigment on King's B medium. Among 22 isolates of the fluorescent pseudomonads, isolates PF4, PF11, and PF19 showed the highest production of fluorescent green pigments around their colonies and introduced as the superior isolates. These isolates were identified based on several biochemical tests such as oxidase, arginine dihydrolase, KOH string test, oxidative-fermentative test, hypersensitive response (HR), levan, nitrate reduction, catalase, pectinase, lecithinase, gelatinase, starch hydrolysis, metabolism of carbohydrates (glucose, fructose, galactose, sucrose, trehalose, xylose, arabinose, sorbitol, adonitol, meso inositol, ethanol, and glycerol), etc. The pyoverdine amount produced by the superior isolates was evaluated using succinate medium and optical spectrometry method set at 400 nm based on a completely randomized experiment with three replicates. Reshingari savory seeds were also collected from its natural habitats located in Mehran County. Two months after planting the seeds in the seedling trays under greenhouse conditions, the plant’s 16-leaf seedlings were transferred to the research farm of the Research Institute of Forests and Rangelands which is located in Tehran province. Each two-year-old plant was treated with a suspension (107 CFU/ml) of the superior isolate by adding to the soil based on a randomized complete blocks design (P≤0.05). Seven months after applying the treatments, which coincided with the full flowering stage in the third year of planting, several vegetative traits such as the plant height, canopy diameter, the total number of branches per plant, the number of flowering branches, the shoot fresh and dry weights, the root fresh and dry weights, the root length and diameter were measured. Three replicates were randomly selected from three blocks for each treatment. The plots were 2 x 2 meters with a distance of two meters between them, and there was a 3-meter distance between the blocks.

According to the results, isolates PF4, PF11, and PF19 belonged to biovars II, III, and V of Pseudomonas fluorescens, respectively. The highest concentration of siderophore pyoverdine (0.42 mg/ l) was significantly produced by isolate PF11 (P<0.05). The highest plant height (56.4 cm), canopy diameter (61.6 cm), total number of branches per plant (14.7), number of flowering branches (6.33), shoot fresh weight (161.67 g) and dry weight (114.3 g), root fresh weight (11.21 g) and dry weight (7.22 g) were observed in PF11 treatment and the highest root length (14.53 cm) and diameter (0.45 cm) were belonged to PF4 treatment.

According to the findings of the present study, the treatment of Reshingari plants with the growth-promoting rhizobacterium PF11 belonging to the group of fluorescent pseudomonads with the ability to produce the microbial siderophore pyoverdine improved the plant growth parameters under field conditions. It was also found that the efficiency of the bacterial isolates belonging to the P. fluorescens species can be significantly different from each other in terms of influencing the plant growth parameters. Therefore, it is recommended to apply the native and compatible isolate PF11 as an alternative to the use of chemical fertilizers in the cultivation of Reshingari savory.

The rapid growth of the global population has intensified the demand for food production, which has consequently led to a significant increase in the use of chemical fertilizers in agriculture. While these fertilizers have been effective in boosting crop yields, their widespread and prolonged use has raised serious concerns due to their adverse effects on human health, soil quality, water resources, and overall environmental sustainability. These concerns include soil degradation, contamination of water bodies through runoff, and the disruption of natural ecosystems. In response, there has been a shift towards more sustainable agricultural practices that aim to minimize these negative impacts while maintaining or even enhancing agricultural productivity. Biofertilizers have emerged as a promising alternative in this context. Unlike chemical fertilizers, biofertilizers are composed of living microorganisms, primarily beneficial rhizospheric bacteria that can naturally enhance the availability of essential nutrients such as nitrogen, phosphorus, potassium, iron, and zinc to plants. Moreover, these microorganisms produce a range of bioactive compounds including growth-promoting hormones, siderophores, and antibiotics, which can stimulate plant growth, enhance resistance to pathogens, and improve soil health. The objective of this article is to provide a comprehensive review of the various components of biofertilizers, discussing their potential benefits, the challenges associated with their use, and their future prospects in the context of sustainable agriculture.

This study explores the different components of biofertilizers, focusing on their composition, properties, and applications. The types of biofertolizers reviewed include powders, granules, liquids, polymer-encapsulated forms, dried fluid beds, and gels. Each of these biofertolizers offers unique advantages and faces specific challenges that can impact the effectiveness of them. For instance, powder and granular biofertolizers are popular due to their ease of handling, transportation, and storage, but they may suffer from reduced microbial viability over time. Liquid biofertolizers, while offering a more immediate and homogenous distribution of nutrients, are more susceptible to contamination and require more stringent storage conditions. The article also discusses the critical aspects of biofertilizer production, including the selection of appropriate microbial strains based on their functionality and compatibility with target crops and soil types. The choice of carrier materials (organic, inorganic, liquid, or synthetic) plays a significant role in maintaining the viability and activity of the microorganisms. Additionally, the article examines the use of additives such as adhesives, stabilizers, and protective agents that can enhance the biofertolizer's performance. The production process involves several essential steps: the preparation and sterilization of carriers to eliminate contaminants, the inoculation and growth of microbial strains under controlled conditions, and the packaging of the final product to ensure shelf-life and ease of application.

The findings from this review indicate that the choice of biofertilizer components greatly influences its effectiveness in the field. Powder and granular biofertilizers are found to be suitable for large-scale applications due to their stability and ease of use; however, they often face biofertilizers related to the survival rate of the beneficial microorganisms during storage and application. Liquid biofertilizers, on the other hand, provide a rapid supply of nutrients and are easier to apply in irrigation systems, but their efficacy can be compromised by contamination risks and the need for cold storage. More advanced biofertilizers, such as polymer-encapsulated, dried fluid bed, and gel forms, show promising results in protecting microorganisms from environmental stresses such as desiccation, and temperature fluctuations. These formulations can provide controlled release of nutrients and ensure longer shelf life. However, their production is often more complex and costly, requiring advanced technology and materials. The research highlights that an integrated approach combining multiple components or optimizing specific formulations based on local conditions and crop requirements could enhance the effectiveness and adoption of biofertilizers in sustainable agriculture.

The development and optimization of biofertilizer components are crucial for their success in sustainable agriculture. High-quality biofertilizers that ensure the survival and activity of beneficial microorganisms can significantly reduce the dependency on chemical fertilizers, thereby minimizing their negative environmental and health impacts. The growing interest in sustainable agricultural practices, coupled with increasing public awareness of the benefits of biofertilizers, suggests a promising future for these products. Further research and innovation are needed to address the challenges associated with their production, formulation, and application to ensure maximum efficacy and build trust among farmers. Technological advancements, such as improved encapsulation techniques and the use of novel carrier materials, are expected to enhance the performance of biofertilizers, making them a key component of future agricultural systems aimed at protecting soil and environmental health.

Drought stress is a major limiting factor in global agricultural productivity, significantly affecting plant growth and yield by altering the plant’s morphological, physiological, and biochemical characteristics. These changes, including reductions in chlorophyll content, leaf water status, metabolite content, compromise plant development and crop output. One promising approach to mitigating the detrimental effects of drought stress is the use of biofertilizers, particularly arbuscular mycorrhizal (AM) fungi and plant growth-promoting rhizobacteria (PGPR). AM fungi establish symbiotic relationships with plants, improving water uptake and nutrient absorption, while PGPR enhance plant growth through various mechanisms, including the production of enzymes and stress-relieving compounds. Although numerous studies have demonstrated the efficacy of biofertilizers in improving plant resilience to drought, there is a significant knowledge gap regarding the comparative effectiveness of different types of biofertilizers. Specifically, it remains unclear whether fungal-based or bacterial-based biofertilizers are more effective, and whether liquid or powder formulations provide superior benefits. Moreover, there is limited understanding of the role of soil microbial processes, such as enzyme activities in the rhizosphere, in the plant’s adaptive response to drought conditions. This study aims to fill these gaps by investigating the effects of different biofertilizer types and formulations on drought tolerance in wheat, focusing on key physiological, biochemical, and microbial indicators.

For these purposes, a split-plot experiment was conducted based on a randomized complete block design with three replications under field conditions. The main plots consisted of three irrigation treatments: 100%, 85%, and 65% of the plant's water requirement, representing full irrigation, mild water stress, and severe water stress, respectively. The subplots included different biofertilizer treatments: no biofertilizer (F1), Pseudomonas fluorescens producing ACC-deaminase (F2), P. fluorescens without ACC-deaminase production (F3), AM fungus in liquid form (F4), and AM fungus in powder form (F5). Samples of flag leaves, roots, and rhizospheric soil were collected at the spike emergence stage. Several parameters were measured, including chlorophyll, carotenoid, proline, relative water content (RWC), membrane stability index (MSI) in the flag leaves, root colonization percentage, and rhizosphere enzyme activities such as acid phosphatase, alkaline phosphatase, and β-glucosidase. These indicators were chosen to evaluate both the direct effects of biofertilizers on plant drought tolerance and the associated microbial processes in the soil.

The results indicated that among the bacterial biofertilizers, only the application of F2 under severe water stress led to a 5% decrease in proline, a 6.5% increase in chlorophyll a, a 6% increase in total chlorophyll, a 16% rise in carotenoids, as well as a 10% increase in β-glucosidase activity and a 13% increase in acid phosphatase activity compared to the treatment without biofertilizer. The powder form of AM fungus (F5) proved to be the most effective in colonizing the roots of wheat. Specifically, root colonization with F5 was 13%, 19%, and 8% higher at irrigation levels of 65%, 85%, and 100% of the plant's water requirement, respectively, compared to the liquid form of AM fungus (F4). Overall, fungal biofertilizers outperformed bacterial biofertilizers in enhancing the physiological characteristics of wheat. For instance, under severe water stress, the F5 and F4 treatments increased RWC by 8.5% and 6%, MSI by 20% and 14%, chlorophyll a by 1% and 14%, and total chlorophyll by 12% and 10% compared to the treatment without biofertilizer, which were significantly higher than the bacterial biofertilizers. Among the fungal biofertilizer formulations, the powder form of AM fungus was more efficient than the liquid form in increasing wheat's drought tolerance. The powder form also improved β-glucosidase activity under both severe and mild water stress conditions and increased the activity of all the investigated enzymes under full irrigation. A stepwise linear regression model revealed that that among the biochemical and physiological characteristics of the flag leaf of the wheat, the amount of proline and carotenoid are the most important key variables affecting the β-glucosidase activity with relative importance index of 25.8% and 18.9%, respectively. Also, the amount of total chlorophyll and chlorophyll a had the greatest effect on the amount of alkaline and acid phosphatase activities.

The findings of this study underscore the superior effectiveness of fungal biofertilizers, particularly in powder form, in enhancing drought tolerance in wheat. The powder form of AM fungi was more efficient than the liquid form in promoting root colonization and increasing enzyme activity in the rhizosphere, leading to improved physiological and biochemical traits in the wheat plants. This formulation likely contains a greater diversity of AM fungal species, which may contribute to its enhanced performance. The positive feedback loop observed between rhizospheric enzyme activities and plant physiological traits suggests that biofertilizers, particularly AM fungi, can play a crucial role in improving the drought resilience of crops in water-limited environments.

Hazelnut (Corylus avellana L.) is considered one of the most prominent species of Ardabil Fandoghlou forest in. This species is ecologically and economically important and is one of the most valuable medicinal plants in traditional medicine and pharmaceutical industries. Unfortunately, in recent years, conversion of use, livestock grazing, fire and cutting of trees have been effective factors in the destruction of this valuable forest. Considering the ecological and economic importance of the hazelnut species, it is very important to restore the habitats of this species through seedlings. On the other hand, the success of planting depends a lot on the establishment and survival of planted seedlings (Spehbadi, 2019), which chemical fertilizers are used most of the time. The use of these fertilizers has had adverse effects on the soil ecosystem, and in addition to destroying beneficial soil microorganisms and the poor growth of seedlings, it has resulted in several adverse effects on the environment and human health. The use of growth-promoting microorganisms is considered one of the biological methods to increase the yield of plants and reduce the consumption of chemical fertilizers. Trichoderma spp. have been known as plant growth promoter besides its primary function as pathogen inhibitor. This research was conducted with the aim of the effect of T. harzianum on of physiological properties of hazelnut seedlings in field conditions.

At the beginning of May 2016, in Ardabil Hazelnut Nursery, the soil around the roots of potted hazelnut seedlings, produced from the three sources of Fandoglou (Ardabil Hazelnut Forest), Makesh (Guilan) and Makidi (Arasbaran) with T. harzianum were inoculated. Then, in November 2017, the one-year-old hazelnut seedlings were transferred to the area adjacent to the nursery located in lands of the forest edge with an area of 4050 m2. Then they were planted in factorial arrangement in a randomized complete block design (with the two factors mentioned above including three seed sources and T. harzianum inoculation and no inoculation or control in three replications). The number of seedlings in each replication was 25 (450 seedlings in total), which were planted a distance of 3 × 3 m in rain-fed conditions. The characteristics of leaf area, specific leaf area and physiological properties including leaf area, specific leaf area, photosynthesis rate, stomatal conductance, transpiration rate, water use efficiency (WUE) and chlorophyll content were measured. For this purpose, in each treatment, three seedlings were randomly selected and measurements were taken on the fourth and fifth healthy and fully grown mature leaves from the tip of the plant using a photosynthesis meter on a sunny day (mid-September) and it was done in the open air under natural conditions of temperature, light and relative air humidity between 9:30 and 11:30 while the constant leaf temperature was between 20 and 25 o C.

After four years, all measured properties were significantly affected by fungal inoculation. Inoculated seedlings from all three origins displayed higher values for all investigated traits compared to controls. The highest of leaf area (22.4 cm2), specific leaf area (119.2 cm2 g-1), photosynthesis rate (18.45 µmol Co2 m2 s-1), stomatal conductance (0.198 mmol m2 s-1), transpiration rate (mmol H20 m2 s-1), water consumption efficiency (7.69 µmol Co2 mol H2o -1) and chlorophyll content increased by (26.49 %) were obtained from Seedlings of Fandoglou origin inoculated with T. harzianum in compared to the control (non- inoculated seedlings). The lowest of leaf area (12.4 cm2), specific leaf area (85.5 cm2 g-1), photosynthesis rate (8.01 µmol Co2 m2 s-1), stomatal conductance (0.101 mmol m2 s-1), water consumption efficiency (2.41 µmol Co2 mol H2o -1) and chlorophyll content increased by (14.15 %) were observed from Seedlings (non- inoculated) of control with origin of Makidi.

The present study showed that the hazelnut seedlings of the origin of Fandoghlou under the influence of T. harzianum inoculation were superior in terms of the studied traits in comparison to the two origins of Makseh and Makidi. Therefore, for the production of healthy and strong hazelnut seedlings in the nursery, the origin of the Fandoghlou can be used. An important point in inoculation of seedlings with T. harzianum fungus was the increase in the water use efficiency (WUE) of of hazelnut seedlings with the origin of Fandoghlou up 150% compared to the control seedlings. So, it can be concluded that by increasing the rate of photosynthesis rate and reducing transpiration rate, inoculated seedlings increase the efficiency of water use and can have more vegetatative growth and suitable physiological traits in reforestation or create of hazelnut gardens in the prone lands of Fandoghlou forest. Keywords: Arasbaran, Corylus avellana, Stomatal conductance, Specific leaf area.

Crude oil consists of aliphatic, aromatic, and heterocyclic compounds, all of which are toxic to life forms. Therefore, oil pollution is a significant environmental concern. Due to widespread use, accidental spills, transportation, and refining processes, crude oil contamination is relatively common worldwide. Methods for remediating oil-contaminated soils include biological, chemical, and physical approaches. While chemical and physical methods have many disadvantages, bioremediation is a promising and effective approach for treating oil-contaminated soils. Bioremediation is the natural ability of microorganisms and their enzyme systems to degrade, break down, and convert hydrocarbons into less toxic substances. This method is considered the least harmful and most cost-effective way to clean the environment. Different microbial genera are known to degrade hydrocarbons. Among these, Bacillus stands out as a Gram-positive, rod-shaped bacterium capable of producing spores in aerobic environments. Belonging to the class Bacilli and the family Bacillaceae, Bacillus can form endospores under stressful environmental conditions, allowing them to remain dormant for long periods. This unique characteristic makes Bacillus particularly advantageous for bioremediation in oil-contaminated environments. The current review article focuses on the recognition and potential of biodegradation of petroleum compounds by oil-eating bacteria, especially the genus Bacillus. It is hoped that this review will enhance our understanding of oil pollution's impact on biological communities and microbial remediation of oil-contaminated soil.

All the articles used in this review were prepared from online sources (Google, Google scholar, SID, CAS, Science Direct, Wiley online Library, etc.), and from the publishers Elsevier, Wiley Online Library, Frontiers, Springer, ehp, Taylor and Francis Online, MDPI, ACS Publication, Nature, Civilica, etc.). This article is based on 169 JCR international journals and scientific journals. This review article briefly includes sections 1-The effect of crude oil on soil microorganisms, 2-Oil pollution in Iran, 3-The importance of bioremediation of petroleum compounds, 4-Mechanisms of remediation of oil-contaminated soils, 5-Aerobic and anaerobic degradation pathways of n-alkanes, 6-Researches conducted in the field of bioremediation of petroleum hydrocarbons in Iran, 7-Characteristics of Bacillus in oil degradation, and 8-Bioremediation of oil-contaminated soils in Iran with the approach of using Bacillus.

Various bacterial genera, such as Achromobacter, Acinetobacter, Alcaligenes, Arthrobacter, Actinomycetes, Pseudomonas, Enterobacter, Micrococcus, Staphylococcus, Mycobacterium, Rhodococcus, Vibrio, Sphingomonas, Lactobacillus, and Serratia, are known to degrade hydrocarbons. These bacteria destroy hydrocarbons and purify the soil through the function of their enzyme system and secretion of various compounds such as biosurfactants through various pathways and mechanisms. There are two main mechanisms for the breakdown of hydrocarbons: aerobic and anaerobic pathways. In aerobic mechanisms, oxygen is used as the electron acceptor, while in anaerobic conditions, sulfate and nitrite receive the electrons and complete the process. Bacillus species are typically mesophilic, thriving at temperatures between 30-45°C. Some thermophilic species can grow at higher temperatures, up to 65°C. Spore formation in Bacillus involves asymmetric cell division, producing an endospore and a mother cell, which enables the bacterium to survive harsh conditions. Bacillus species can utilize hydrocarbons as carbon and energy sources, making them commonly found in oil-polluted soils. Several Bacillus species, including B. polymyxa, B. cereus, B. subtilis, B. badius, B. licheniformis, B. cibi, B. megaterium, and B. stearothermophilus, have demonstrated the ability to degrade petroleum hydrocarbons. These bacteria can tolerate a wide range of environmental conditions, such as varying pH, temperature, and salt concentrations, which few organisms can endure. They are highly resistant to environmental stressors like nutrient scarcity, dryness, radiation, hydrogen peroxide, and chemical disinfectants. The production of endospores also provides a distinct advantage for hydrocarbon biodegradation. Furthermore, Bacillus species produce a variety of biosurfactants, particularly lipopeptides, which enhance the solubility and bioavailability of hydrocarbons, thereby increasing bioremediation efficiency. Since biosurfactants are biodegradable and have low environmental toxicity, producing these powerful, stable compounds using low-cost carbon sources could significantly advance bioremediation of oil-contaminated soils. Bacillus also produces key degradative enzymes, such as lipase, hydroxylase, dioxygenase, monooxygenase P450, and protease, which play crucial roles in breaking down petroleum compounds. It has been reported that species like B. subtilis, B. pumilus, B. licheniformis, and B. megaterium can degrade alkanes, BTEX, and PAHs by secreting these enzymes. The hydrocarbon groups in oil can combine with soil phosphorus, leading to phosphorus depletion. Since phosphorus limitation is a key constraint in bioremediation of oil-contaminated soils, phosphorus-solubilizing Bacillus species such as B. subtilis, B. cereus, B. thuringiensis, B. pumilus, and B. megaterium, which secrete organic acids like gluconic, lactic, acetic, succinic, and propionic acids, can alleviate this problem. Research conducted in Iran and the international scientific community shows that this bacterium is capable of degrading various oil compounds by up to 99% within 10 to 30 days in liquid media. Additionally, in soil, Bacillus can degrade petroleum hydrocarbons by 20% to 80% over a period of 15 to 180 days.

In conclusion, various bacterial genera, particularly Bacillus species, play a critical role in the degradation of hydrocarbons through aerobic and anaerobic pathways. Bacillus, known for its resilience to environmental stressors and ability to form endospores, is highly effective in bioremediation, especially in oil-contaminated soils. These bacteria produce essential enzymes and biosurfactants, such as surfactin, which significantly enhance the breakdown of petroleum hydrocarbons. Moreover, phosphorus-solubilizing Bacillus species help address nutrient limitations in contaminated environments, further boosting their potential in environmental clean-up. Their remarkable efficiency, with degradation rates of up to 80% in soil, highlights their importance in sustainable bioremediation efforts worldwide.

Soil, as one of the elements of the ecosystem, plays a major role in changing and diversifying forest species, and on the other hand, the type of vegetation also plays a significant role in changing and transforming the physical, chemical and biological characteristics of soils. In addition to these, soil microbial communities play a very important role in the decomposition and stabilization of organic matter in the soil, as well as in the mineralization of its nutrients, and due to their great diversity, they provide very important services in the soil. Therefore, their correct and accurate evaluation based on efficient and reliable indicators can provide useful information. In this research, the indices of basic microbial respiration, stimulated microbial respiration, nitrification potential, microbial biomass carbon and metabolic fraction were evaluated under the influence of stem. In order to obtain the soil quality indicators, the biological characteristics of the soil were investigated. Soil sampling was taken for each selected trunk tree from a depth of 0-15 cm under the tree crown (in the distance between the trunk and the end edge of the crown) in the east direction of the tree. 15 soil samples were randomly taken from the depth of 0 to 15 cm in each sample plot for this existing and dominant tree species (one to three species) and all three soil samples in each sample plot were well mixed and made into one composite sample for each sample plot. Species were transformed (five soil samples for each species). Also, 15 soil samples were randomly taken from the depth of 0 to 15 cm inside each sample plot, outside the crown and in the place outside the cover, and all three soil samples were mixed well and made into one composite sample for the sample plot. transformed (5 soil samples for each sample plot). In this research, two treatments were used, one under the canopy and the other outside the canopy with pasture cover. A total of 30 soil samples were collected, 15 samples under the canopy and 15 outside the canopy with pasture vegetation, in each treatment three samples were combined and converted into one sample. In fact, for each treatment, 5 samples were sent to the laboratory, and the coordinates of each sample were recorded in order to prepare a sampling map. Immediately after sampling, a part of the soil samples was kept in plastic bags and the other part was kept in cold conditions (4°C) and transferred to the laboratory for further analysis.Send feedback. The results showed that the effect of treatment on basic respiration, clay percentage, silt percentage and sand percentage was not significant. The effect of treatment on stimulated respiration, microbial biomass carbon and nitrification potential was significant at 1% probability level and metabolic fraction at 5% probability level. Also, the average value of stimulated respiration, nitrification potential and metabolic deficit in the soil sample under the baneh tree was higher than outside the tree. Most of the biological characteristics in the soil were affected by the stem and showed significant changes compared to the control, which will indicate the effect of the application on the life rings in the soil. In general, the results indicated that most of the biological characteristics in the soil were affected by the log and showed significant changes compared to the control, which would indicate the effect of the application on the life cycles in the soil. The trend of changes in stimulated respiration and the potential of nitrification and metabolic deficit under the canopy was not consistent with the trend of changes in microbial biomass carbon. Due to the increase in the characteristics of stimulated respiration and the potential of nitrification and metabolic fraction under the crown of the corm cover in the region, these indices can be useful for evaluating the soil quality of the region. While the reduction of microbial biomass carbon under the canopy compared to the control soil (outside the tree canopy), could be due to the change in the type of substrate or the difference in the diversity of the microbial population in the soil under the canopy or outside it. The results of this research show that in evaluating soil quality, improving soil fertility and managing plant nutrition, the role of soil biological characteristics cannot be ignored. On the other hand, having the biological parameters of the soil, as a knowledge-based approach with accessibility and flexibility, more information can be provided to experts and users for decision-making to improve soil fertility and manage root tree nutrition.