Journal of Soil Biology
Year:2021 | Volume:9 | Issue:1|Papers Count:8

Plant growth promoting rhizobacteria with ACC deaminase activity can be applied for stimulating plant growth under tension situations. In the present study, bacterial isolates were isolated from wheat rhizosphere in three provinces of Zanjan, Kurdistan and Hamedan and then screened for ACC deaminase production and salinity tolerance. Six isolates out of 167 isolates were able to degrade ACC to alpha-keto-butyrate and ammonia and the K78 isolate was selected as superior isolate. A completely randomized design with factorial arrangement was carried out on wheat plant in a greenhouse experiment. Experimental factors include: five salinity levels (1. 3, 8, 12, 14, and 16 dS. m-1 ), three bacterial inoculation levels (no inoculation (B0), inoculation with salinityresistant isolate and ACC deaminase production capacity (B1), inoculation with salinity-resistant isolate without ACC deaminase production capacity (B2). The results showed that salinity had a significant and negative effects on growth and nutrient uptake and decreased shoot length. The K78 isolate increased shoot length (21. 5 %) and potassium uptake (15 %) significantly compare to B0 treatment but had no significant effect on sodium uptake. Overall, it can be concluded that inoculation of K78 isolate can reduce the negative effects of salinity on growth indices and the nutritional conditions of wheat.

Drought is one of the most important environmental stresses that adversely affect the plant growth and crop production. Arbuscular mycorrhizae fungi help their host by absorption of water and mineral nutrition. In order to evaluate mycorrhizal fungus and water deficit stress on growth characteristics, chlorophyll content and root colonization percentage of almond (Prunus amygdalus) rootstock, a completely randomized design with factorial arrangement was conducted with three replications in agricultural and natural research center of Shahrekoard. The treatments consist of two levels of mycorrhizal fungus (with (M1) and without (M0) mycorrhizal fungus), four types of rootstock (bitter, local Shorab 2, GF and GN) and four levels of water deficit stresses (Control (I0), slight (I1), moderate (I2) and severe (I3)). The results revealed that the rootstock types had significant effects on studied parameters and the maximum measured parameters was observed in GF rootstock treatment. Water deficit stress also had significant effects on examined parameters. With increasing water deficit stress, root colonization percentage and root dry weight decreased significantly. Mycorrhizae fungi treatments increased root dry weight and root colonization percentage 27 and 40 percent respectively. The maximum stem length, stem diameter and plant dry weight were observed in GF +I1 treatment. The highest amount of root colonization percentage (74. 5 %) was achieved in I1 + M1 treatment. Therefore, based on the results, the mycorrhizal fungus increased the growth properties of almond rootstock and reduced the harmful effects of water deficit stress.

Periphytons are the most important microorganism communities which can be found almost in all aquatic systems. Periphytons play important roles in ecological functions of an ecosystem. They are composed of multilayered consortia of photoautotrophs (e. g. unicellular and filamentous cyanobacteria, benthic diatoms and green microalgae) and heterotrophs (bacteria, fungi and protozoa). Due to the role of periphytons in the processes of nitrogen fixation and dissolution of insoluble phosphorus and potassium, Samples of sediment, water and periphytons collected and investigated from three lagoons in Fashtam, Tazesel and Qalewersel in Gillan province. Results showed that Chlorophyta, Bacillariophyta and Cyanobacteria constituted 26. 24%, 56. 06% and 17. 69% of the periphyton components in Qalewersel lagoon, respectively. In the Fashtam lagoon, the Chlorophyta, Charophyta, Euglenozoa, Ochrophyta, Bacillariophyta, and cyanobacteria species formed 38. 48%, 20. 58%, 1. 72%, 1. 74%, 19. 68% and 19. 52% of the periphyton components, respectively. Also, in the Tazesel lagoon, Chlorophyta, Euglenozoa, Bacillariophyta and Cyanobacteria constituted about 13. 93%, 0. 56%, 51. 9% and 33. 6% of components of periphyton, respectively.

The aim of this study was to evaluate the changes in proteases and alkaline phosphatase activities, organic carbon content, total nitrogen and phosphorus in winter and summer time in the coastal soils of Shadegan wetland in 2019-2020. Two sampling sites including site A with dominant vegetation and site B wetlands without vegetation were selected. Soil samples were colected using ASTM standard number D2488. The results of analysis of variance showed that seasonal changes, vegetation and soil depth had a significant effect on total nitrogen, phosphorus and protease and alkaline phosphatase activity (P<0. 001). Seasonal changes did not have a significant effect on the amount of soil organic matter, while vegetation and soil depth significantly affected the amount of soil organic carbon in the coastal soil of Shadegan wetland (P<0. 001). Nutrient elements and activity of extracellular enzymes (protease and alkaline phosphatase) in vegetated soils were higher than bare soils. According to the results, the activity of protease (2. 69 µ mol/gh) and alkaline phosphatase (3. 5 mg/PNP/gh) enzymes in topsoil (0-15 cm) with vegetation was higher in summer time compare to the bare soils. These results can be related to total nitrogen, phosphorus and soil organic carbon (P<0. 05) which had higher values in the summer time. Finally, principal component analysis and Spearman correlation confirmed a strong and positive relationship between total nitrogen, total phosphorus and soil organic carbon (P<0. 001) with the biological activity of protease and alkaline phosphatase enzymes.

Vegetation type changes some soil properties such as bulk density, nutrient absorption and soil organic carbon. Nutrition management of lawn plant is an important factor which affects soil properties in lower layers. The application of biofertilizers enhance the quality of soil and enhance the growth of lawn plant and in addition they are ecofriendly. The purpose of this study was to investigate the effect of urea and biofertilizer containing nitrogen-fixing bacteria (Pantoea agglomerans) on some quality characteristics of soil under lawn plant cultivation. This experiment was conducted in a completely randomized design in a greenhouse condition with three replications. Treatments include: 1-Control (Br), 2-lawn plant cultivation (Speedy Green) by conventional method (Gr), 3-lawn plant + urea (GrU), 4-lawn plant + biofertilizer containing Pantoea agglomerans (GrPA), and 5-lawn plant + Pantoea agglomerans + growth promoting bacteria (GrPP). The fresh weight of lawn plant was measured along with some soil properties. The results showed that lawn plant and application of biofertilizer containing Pantoea agglomerans shaped larger soil aggregates than control but they had no significant effect on aggregate stability. Biofertilizers and urea increased the growth of lawn plant. Cultivation of lawn plant increased soil organic carbon, total nitrogen, phosphorus and potassium uptake, but the effect of biofertilizers was not significant. The highest amount of total nitrogen and soil organic carbon observed in urea fertilizer treatment. In general, the use of biofertilizers in lawn plant cultivation is recommended.

To evaluate the effects of Pseudomonas fluorescens strain 169 and Funneliformis mosseae on drought resistance of mung bean a Randomized Complete Block Design (RCBD) with four replications conducted in a greenhouse condition at Islamic Azad University of Miyaneh branch, Iran, in 2016. The drought stress treatments included: normal irrigation (control), stopping irrigation in flowering stage, stopping irrigation in pods formation stage. Inoculation treatments included: non-inoculation (control), inoculation with Funneliformis mosseae, Pseudomonas fluorescens strain169 and Funneliformis mosseae + Pseudomonas fluorescens strain169. According to variance analysis of data, effects of drought stress on the majority of morphophysiological traits except phosphorous content, the number of seeds per pod were significant. Interaction effects of inoculation and drought stress based on plant height, relative water content and amount of nitrogen were significant respectively in statistical levels of P≤ 0. 01, P≤ 0. 05 and P≤ 0. 01 respectively. High amount of root colonization percentage (55. 4%) observed in plants inoculated with Pseudomonas fluorescens strain169 which was nonsignificant with co-inoculated ones. Based on mean comparison, drought stress reduced the majority of morphophysiological traits significantly. All inoculation treatments had the highest value in comparison with control. Co-inoculation of Funneliformis mosseae and Pseudomonas fluorescence 169 was more effective in improving the number of seeds per pod. Funneliformis mosseae inoculated plants had 17. 4%, 29. 5% and 28. 5% enhancement in plant height, the number of leaves for each plant and phosphorous amount in comparison with control respectively.

Medicinal plants have an important role in advancing national, regional and global goals for achieving health, drug self-sufficiency, employment creation and economic development. Since, quality and quantity improving of medicinal plants is aimed therefore it seems that the application of biofertilizers is the most compatible with that purpose. The objectives of this research were to isolate endophytic bacteria from leaves and stems of medicinal plants and to evaluate their growth promoting traits and assess their potential as biofertilizers. Healthy basil, rosemary, savory and pennyroyal plants were collected from area around Ardabil city and transferred to the laboratory. The endophytic bacteria isolated using serial dilution technique on the nutrient agar. Different colonies according to the appearance, color, margin and growth rate were selected, purified and kept at 4 ° C. Then, the ability of the isolates to produce Indole Acetic Acid (IAA), solubilization of tricalcium phosphate, hydrogen cyanide and protease were evaluated. In this study, 99 endophytic bacteria were isolated from the medicinal plants. Finally, According to the morphological properties and growth rate, 53 different isolates (13 isolates from each plant) were selected. Results revealed that all the endophytic bacteria were able to produce IAA at 100 mg l-1 L-tryptophan. The most potent bacteria in terms of IAA production were P4, P3 and B1 isolates (with production of 15. 31 mg l-1, 11. 55 -1 mg l-1 and 12. 97 mg l, respectively). All of the examined isolates had the ability to dissolve tricalcium phosphate. The highest ability of solubility (646. 52 mg l-1 ) was observed in S5 isolated from Savory. The bacteria isolated from Rosemary had the lowest ability to dissolve tricalcium phosphate. All bacterial isolates were able to produce hydrogen cyanide. In assessing the ability of isolated endophytic bacteria to produce protease enzyme, clear zone formation was observed only around the colonies of S1, S4, B9, B12, B3, B11, R7, P6 and P4. It is suggested that the effects of superior isolates on growth and yield of medicinal plants used in this study should be investigated in greenhouse and field conditions before any recommendation.

In order to investigate the diversity and population fluctuations of soil mesofauna (Acari and Collembola) of conifers (cypress and pine trees) at Ilam province, Iran, soil samples monthly (0– 5 and 5– 10 cm) were collected during September 2018 to September 2019. The soil mesofauna were extracted using a Berlese funnel and they were counted and identified. The number of arthropods was compared in different soil layers and in different seasons of the year. The analysis of variance of data showed that soil layers and seasons had significant effect on the population densities of soil mesofauna in both cypress and pine trees (P≤ 0. 01), but their interaction did not vary significantly. Based on the means comparisons, the highest and the lowest values of population density of soil mesofauna were belonged to cypress trees with values of 26. 5± 8. 22 (at autumn) and 0. 74± 0. 15 (at summer). In addition, based on the mean comparison, the highest and the lowest amount of population density of soil mesofauna in pine trees were 4. 31± 1. 26 (at autumn) and 0. 63± 0. 14 (at spring). Diversity of arthropods was calculated by using biodiversity indices. The results showed that the most diversity of species based on Shannon-Wiener and Simpson indices observed in seasons and sampling area (cypress and pine trees) with values of 3. 77 and 0. 97 for pine and summer time and the least diversity detected with 2. 44 and 0. 83 for cypress and spring time, respectively. Also, the highest amount of species richness of Margalef (11. 68) related to the soil of pine trees in autumn season and lowest amount (7. 89) related to the soil of cypress trees in spring season. The highest values of Pielou evenness index (0. 97) related to soil of pine trees in summer time and lowest value (0. 64) related to the soil of cypress trees in spring time. Generally, the calculated biodiversity indices in the soil of pine trees were higher than in the soil of cypress trees, which could be more widely used in the forestry system.