مجله زیست شناسی خاک
سال دهم شماره 1 (بهار و تابستان 1401)

Quinoa (Chenopodium quinoaWilld.) is a high-yielding pseudo-cereal crop, belonging to the Chenopodiaceae plants, shows tolerance to salinity stress. As a chenopod plant, it could not establish a symbiosis relation with mycorrhizal fungi, but there are evidences that the Serendipitaindica (endophytic fungus) could enter the root and more likely improves the tolerance of quinoa against salt stress. This study was performed as a pot experiment in Completely Randomized Factorial Designs (CRFD) with three replications in a sterilized sandy loam soil. Experimental factors included two levels of S. indica (inoculated and non-inoculated) and salinity levels of 1.47 (initial electrical conductivity of soil), 5, 10, 20 and 30 dS/m. The interaction effect of salinity stress and fungal inoculation was significant for studied traits in both shoot and root (P <0.05), except for the concentrations of nitrogen and phosphorus in the root. The concentrations of phosphorus, potassium, calcium and magnesium, growth traits and percentage of root colonization in quinoa were significantly reduced by increasing salinity levels (P <0.05). S. indica increased root dry weight in control, 5 and 10 dS/m by 23.45, 25.66 and 25.57%, compared to no-fungal treatment, respectively. At initial electrical conductivity (1.47dS/m), shoot dry weight increased by 9% in inoculated plants compared to the non-inoculated treatment. Inoculation with S. indica reduced the concentration of root sodium at salinity levels of 10, 20 and 30 dS/m by 30.49, 66.78 and 43.55%, respectively, compared to the non-inoculated treatment. In the aerial part, the fungus could reduce the sodium concentration at 10, 20 and 30 dS/m by 20.96, 13.28 and 10.24%, respectively, compared to the treatment without the fungus. Based on the results, inoculation with the fungus significantly increased the concentrations of nitrogen, phosphorus and potassium in shoots at 20 and 30 dS/m.

Lemon (Citrus aurantifolia) is particularly an important tree because its fruits are freshly used and also they are used in the food industries. Lemon tree has high economical value among all other citrus trees. In order to investigate the effects of mycorrhizal inoculation on lemon tree under draught stress, an experiment was carried out in split-block design with three replications. The study area was Darab and the experimental period was two years. The main plots consisted of three levels of irrigation (60 %, 80 % and 100 % of lemon water requirements), and the subplots were three levels of mycorrhizal inoculation (0, 1 and 2 kg per tree). Mycorrhizal inoculant was prepared by mixing of three species Funneliformis mosseae, Rhizophagus irregularis and Claroideoglomus etunicatum. The results showed that moisture stress, regardless to mycorrhizal inoculation, caused significant decrease in the majority of the measured traits, except Water use efficiency (WUE) that showed the opposite trend. Main effects of mycorrhizal inoculation increased the majority of measured traits. In 2 kg per tree inoculation treatment, fruit yield, fruit weight, leaf chlorophyll, leaf phosphorous concentration, relative water content, WUE and root colonization were significantly increased (22.1, 53.3, 42.0, 19.5, 15.3, 24.0 and 508 percent, respectively). Under the conditions of mild and sever moisture stresses, the use of mycorrhizal inoculant (1 and 2 kg per tree)  improved some of the measured traits, such as fruit yield that increased 20.2% and 37.6%, respectively. As a general conclusion, using of mycorrhizal inoculation had significant effect on yield and some growth characteristics and increased tolerance to moisture stress probably due to improve P concentration and water relation in plant, such as osmotic adjustment, water hydronic conductivity and stomatal regulation

Due to the importance of mycorrhizal fungi and their ability in colonization of plants, the use of some microorganisms and chemical compounds to improve mycorrhizal activity is an important issue. In this study, an experminet  was conducted as a compeletely randomized factorial desin with  three replications at Valiasr University of Rafsanjan.Three fungal species, Funneliformis mosseae(FM), Rhizophagus intraradices(RI) and Rhizophagus irregalaris (RIr) were applied asmycorrhizal inoculant and the effect of some microorganisms including yeast (Issatchenkia orientalis) and bacteria (Pseudomonas fluorescens VUPf5) as well as chemical compounds such as compost tea, azolla extract, bacterial siderophore, humic acid and amino acid complex on fungal activity and physiological parameters of corn plant (SC750 cultivar) was examined. The results showed that all species of mycorrhizal fungi combined with bacterial treatment and chemical compounds had a significant effect on stem diameter and longitudinal growth, leaf area increase, root weight and dry weight and shoot dry weight. Variance analysis of SPAD showed that there was not significant difference between mycorrhizal and non-mycorrhizal treatments. However, the application of different species of mycorrhizal fungi had a significant effect on the content of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids in compared to the control (without mycorrhizal fungus) treatment. The use of humic acid and compost had the extreme effect on plant growth. Amino acid complex treatment with Rhizophagus intraradices had the greatest effect on chlorophyll a, chlorophyll b and total chlorophyll content. The treatments of yeast and amino acid complex had the greatest effect on carotenoids, respectively..

Land use change is one of the most important factors influencing soil microbial communities which play a pivotal role in most biogeochemical and ecological processes. In order to determine the effect of land use on the composition of soil bacterial communities, High Resolution Melt (HRM) analysis and Denaturing Gradient Gel Electrophoresis (DGGE) were used in three different land uses (orchard land, farmland and shrub land) in Jiroft plain, Iran. In the case of HRM analysis, a real-time PCR device equipped with this technique was used. DGGE technique via DCodeTM Universal Mutation Detection System was conducted to evaluate the composition of soil bacterial communities. The results of HRM as well as the ordination results based on the presence or absence of DGGE bands in soil samples using non-metric multidimensional scaling (NMDS) method showed that the land-use change from shrub land to agriculture (orchard and farm) had a significant effect on the soil bacterial community composition. According to the results of both methods, the soil bacterial community composition in agricultural lands (orchard and farm) was more similar than shrub land. Since HRM analysis is less expensive, easier and has less bias compared to DGGE technique, it is recommended to compare the composition of soil bacterial communities in different samples.

In order to evaluate the potential of native species of saffron arbuscular mycorrhizal fungus under the conditions of irrigation cut stress on its physiological traits, a study was conducted as split plot factorial based on a randomized completely design with three replications in the institute of Soil and Water research in Karaj, during the years 2017-2019. Treatment consisted: Irrigation regime as the main factor in three levels (such as optimal irrigation as control, water interruption at the beginning of the growing season (mild restriction water) and water interruption at the beginning and mid of the growing season (severe restriction water)), organic fertilizer in three levels (no organic fertilizer, vermicompost (20 ton ha-1) and biochar (10 ton ha-1) and Arbuscular mycorrhizal fungal in three levels (no application, isolate a and isolate b) as the subfactor. . Based on the molecular findings, both isolate isolated from saffron rhizosphere belonged to Rhizophagus irregularis. The results of this study showed that the interaction of irrigation regime, organic fertilizer and R. irregularis had a significant effect on all measured parameters. The highest percentage of root colonization (98.7%) was for optimal irrigation treatment with biochar and isolate b. The highest content of chlorophyll a, b and carotenoids (with an average of 5.74, 4.36 and 1.52 μg / ml, respectively) was observed in the optimal irrigation treatment with vermicompost and isolate b. Also, the treatment of severe water restriction with biochar and isolate b increased 253, 82, 95 and 165% of CAT, POD and SOD enzyme activities and proline, respectively, in comparison with the optimal irrigation treatment and no application of organic fertilizer and mycorrhiza fungal, which had the lowest amount of these traits. According to the results obtained from this study, it is argued that the use of biochar and vermicompost fertilizers with isolate b can reduce the destructive effects of soil moisture stress.

Today, fungicides are widely used to prevent or eradicate a variety of pathogenic fungi, but in some cases their use has destructive effects on beneficial microorganisms such as mycorrhizal fungi. Mycorrhizal fungi are among the beneficial microorganisms used in the production of biofertilizers. After mycorrhizal symbiosis, plant features included water and nutrient uptake as well as plant resistance to biotic and abiotic stresses improve. These microorganisms are also used to control soil pathogens. The present study was conducted to investigate the effect of concomitant use of fungicides including benomyl, roralthias, mancozeb and Tilt on the effectiveness of R irregularis in both wheat and corn plants under greenhouse conditions. The experiments were designed as a completely randomized design with five treatments and four replications. The effect of fungicides on the growth characteristics of wheat (Chamran cultivar) and corn (Zeamays, Single Cross 704) and their symbiosis relationship with R. irregularis were investigated. The results showed that the effectiveness of mycorrhizal fungus application was not affected by the concomitant use of fungicides. The application of fungicides also improved some growth characteristics in wheat and corn, although in most cases the differences with the control treatment were not significant. In general, two milliliters per liter of Tilt for wheat and two grams per liter of benomyl for corn can be recommended when using R. irregularis inoculum at the same time

Phosphorus is one of the most important elements required by plants and it has many different roles, including energy production and transfer, increasing rooting, grain production and improving the quantity and quality of agricultural products. Unfortunately, more than 70% of the phosphorus entering the soil through phosphate fertilizers is stabilized and removed from the accessibility of plants. Therefore, phosphorus stabilization has caused the use of more chemical fertilizers and the amount of total phosphorus in the soil has increased and sometimes the entry of elements along with phosphate fertilizer may cause soil pollution. In order to increase the solubility of insoluble phosphates in the soil or to prevent phosphorus stabilization, environmentally friendly phosphate-solubilizing microorganisms (PSM) such as bacteria, fungi, actinomycetes and algae can be employed. These microorganisms are able to convert insoluble inorganic and organic compounds of phosphorus into soluble compounds by various methods such as production of mineral and organic acids, proton production, and secretion of siderophore, chelation and production of phosphatase enzyme. In mineral soils containing large amounts of calcium, magnesium, iron and aluminum phosphates, the production of mineral and organic acids and in organic soils the phosphatase enzymes are mostly effective. Genes encoding phosphate solubility have been isolated mainly from Erwiniaherbicola, Esherichia coli and Morgonellamorgani. Some of these genes include ushA, agp, cpdB and napA. Despite the existing problems, fortunately, good progress has been made in the field of genetic engineering of phosphate-solubilizing microorganisms so that phosphate-solubilizing genes can be transferred to other bacteria. Due to the fact that soils contain both inorganic and organic compounds, it is recommended to use a microorganism with the ability to dissolve both organic and mineral compounds and a mixture of some microorganisms.