Amin Heidarpour Monfared; Mohammad Reza Pourmajidian; Farhad Rejali; Mohammad Hojati; Parvin Ramak
Abstract
Introduction: Unfavorable environmental conditions result in stress in plants and so disrupt their growth and survival. Today, soil microorganisms, especially fungi and growth-promoting bacteria, involved in various biological processes in plant growth and soil nutrient cycling, are suggested to reduce ...
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Introduction: Unfavorable environmental conditions result in stress in plants and so disrupt their growth and survival. Today, soil microorganisms, especially fungi and growth-promoting bacteria, involved in various biological processes in plant growth and soil nutrient cycling, are suggested to reduce the effects of environmental stress. Materials and methods: In order to investigate the effect of drought stress and biological inputs on vegetative characteristics of Celtis caucasica (diameter and height growth, root length, fresh and dry weight of root and shoot, and seedling colonization), a factorial experiment (Mycorrhizal factors in two levels of inoculation with arbuscular mycorrhizal fungi and without inoculation (control), bacteria in four levels of Pseudomonas, Azpyrilum, Azotobacter and control treatments, and drought stress at three levels of field capacity (80, 60 and 40%) was performed in a complete randomized block design and four replications in the greenhouse of the Natural Resources Office in Lorestan Province. Results and discussion: The results showed that the highest diameter growth of Celtis caucasica L. seedlings was observed at moderate drought stress in Pseudomonas-fungi and Azotobacter-fungi treatments with an average of 0.554 and 0.525 mm, respectively. The highest height growth was observed at moderate drought stress in Pseudomonas-fungi and Azotobacter-fungi treatments with an average of 21.55 and 20.55 cm, respectively. The highest leaf area was observed at low drought stress in Pseudomonas-fungi and then with Azotobacter-fungi with an average of 116 and 116/75 cm2, respectively. The least of these traits was observed in high drought stress in the control group and azosperyllium treatment. The highest and lowest root length was observed at moderate drought stress in Pseudomonas and Azotobacter treatments, and at low drought stress in the control group and Pseudomonas-fungi treatments, respectively. The highest root fresh weight was observed at moderate drought stress in Azotobacter and Pseudomonas with an average of 16.7916 and 16.7941 g, respectively. The lowest values were obtained at low and moderate drought stress for the control group. The highest and lowest root dry weight was observed at high drought stress in Azotobacter and Pseudomonas treatments, and at low drought stress in control and Azospirillum-fungi treatments, respectively. The highest fresh and dry weight of shoot were obtained at moderate drought stress in Pseudomonas-fungi and Azotobacter-fungi treatments, and the lowest was observed at low drought stress in control and azosperyllium treatments. The highest percentage of colonization was observed in low drought stress in Pseudomonas-fungi and Azotobacter-fungi treatments with an average of 44. 175 and 42.675%, respectively; and the lowest was observed at high drought stress in the control group with 26.42% and azosperyllium treatments, with 26.695%. Conclusion: Microbial and fungal factors and their interactions increase root colonization, plant growth characteristics, and water uptake and thus increase plant tolerance to adverse environmental conditions such as drought stress.
Bahman Zamani Kebrabadi; Syed Mohammad Hojati; Farhad Rejali; Masoud Esmaeili Sharif; Hamid Reza Rahmani
Abstract
Introduction: Phytoremediation was introduced as an effective, inexpensive and environmentally friendly to remove, displace or disable pollutants from polluted soils. There are numerous physical and chemical methods for the treatment of heavy metal contaminated soils, which in addition to high costs, ...
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Introduction: Phytoremediation was introduced as an effective, inexpensive and environmentally friendly to remove, displace or disable pollutants from polluted soils. There are numerous physical and chemical methods for the treatment of heavy metal contaminated soils, which in addition to high costs, lead to the destruction of the physical and chemical structure and vital activities of the soil. This study was applied in order to investigate the effects of inoculated Arbuscular mycorrhizal fungi of resilience to lead and zinc on some morphological traits (colonization, diameter growth, shoot dry and fresh weight, root dry and fresh weight, height and leaf area) of Elaeagnus angustifolia L. Material and methods: One-year-old seedlings of E. angustifolia species with an average height of 70-50 cm, minimum diameter of 1-1.5 cm and leaf number of at least 30 were provided from Jebel Amelian nursery affiliated to the Natural Resources Office of Isfahan Province. The seedlings were transferred to the greenhouse of the Agricultural and Natural Resources Research Center of Isfahan Province and were kept there for 20 days to adapt to the new conditions. In doing so, six treatments of mycorrhizal fungi (Glomus versifome, G. etunicatum, G. intraradices, G. mossea, composition and control treatments) and five treatments of soil (naturally polluted soil, soil polluted with lead, soil polluted with zinc, soil polluted with lead and zinc, control (without pollution) treatment) were considered. Results and discussion: The results showed that there was a significant difference between the measured variables among the different treatment of mycorrhizal fungi. The highest and lowest colonization were observed for G. mossea (40.5%) and control treatment (25.6%), respectively. For G. mossea, the diameter growth (2.8mm), height (36.1cm) and leaf area index (28.8) increased in comparison to the control treatment. There was a significant difference between shoot dry and fresh weight and root dry and fresh weight in all of the treatment of mycorrhizal fungi. The highest dry and fresh weight of shoot was observed in G. mossea treatment (108.4 and 55 g) and the lowest was observed in control treatment (59.4 and 30.3 g). The highest and lowest of fresh weight were observed in control (95.3) and polluted soil with lead and zinc treatments (78g). Highest values of measured variables in all fungi and soil treatments were belonged to the inoculated treatment of G. mossea and the control treatment, respectively. Conclusion: Results of this study showed that inoculated treatment with G. mossea fungi and control treatment of soil caused the growth enhancement in E. angustifolia. However, there was no significant difference between mean fresh and dry weight of root and leaf area index in different soil treatments. Roots, as absorbent levels of water and food, have great effects on the absorption of water and various salts, and various environmental factors influence the growth of the plant through its effect on root growth. Heavy metal stress is one of the factors limiting root growth which affects plant growth activity. Also, in plants that were inoculated with mycorrhizal fungi, the mean of all measured variables was significantly higher than the control treatment. The highest shoot weight was observed in G. mosseae treatment, which suggests that G. mosseae contributed to the plant's absorption of water and food, especially phosphorus, and increased the accumulation of dry matter and has more efficiency in the biomass production of E. angustifolia.
Mehrcedeh Tafazoli; Hamid Jalilvand; Seyyed Mohammad Hojjati; Norbert Lamersdorf
Volume 15, Issue 2 , July 2017, , Pages 39-54
Abstract
Introduction: The amount of nitrogen compounds released into the atmosphere has increased, and is higher in industrial areas due to the increasing usage of fossil fuels and chemical fertilizers (Gruber and Galloway, 2008). Nitrogen deposition is one the consequences of increasing atmospheric nitrogen ...
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Introduction: The amount of nitrogen compounds released into the atmosphere has increased, and is higher in industrial areas due to the increasing usage of fossil fuels and chemical fertilizers (Gruber and Galloway, 2008). Nitrogen deposition is one the consequences of increasing atmospheric nitrogen compounds. Nitrogen deposition refers to a process that nitrogen compounds in the atmosphere deposit on a solid surface (Cornell et al., 2003). Due to the lack of information about the effects of nitrogen deposition on forest soil properties, the aim of this study was to investigate the effects of simulated nitrogen deposition on soil chemical properties in a maple plantation located at the educational and research forest of Faculty of Natural Resources (Sari). Material and methods: Twelve plots of 20 m × 10 m were established in the study plantation stand. Four nitrogen treatments were considered including zero (control), 50 (low), 100 (medium) and 150 (high) kg N ha−1 year−1. Nitrogen in the form of NH4NO3 solution was manually sprayed onto the plots monthly during one year. Three soil samples were taken seasonally at a depth of 0-10 cm in each plot using a coring method and were transported to the laboratory (Xingren et al., 2017). In the laboratory, the physical properties including water content and soil texture were measured by a weighing and hydrometer method, respectively. Chemical properties of soil including pH and EC were measured by potentiometric and electrical conductivity methods, respectively (Soil to water ratio 1:2.5). Soil organic carbon, total nitrogen, phosphorus and potassium were measured using the Walkley and Black method, Kjeltec System Instrument, Olsen P extracting solution and extracted using ammonium acetate, respectively. Results and discussion: The results showed that the nitrogen deposition had significantly decreased the pH and EC. At the end of the study period, the amount of nitrogen in medium (0.47%± 0.010) and high (0.59%± 0.013) treatments was significantly higher than the control (0.36%± 0.006). The amount of phosphorus in medium (15.95± 0.39 mg kg-1) and high (14.95± 0.43 mgkg-1) treatments was significantly lower than the control (24.97± 1.05 mgkg-1). In addition, nitrogen deposition had caused a significant reduction in soil potassium. The amounts of ammonium (low: 6.04, medium: 7.23 and high: 8.53) and nitrate (low: 7.21, medium: 9.95 and high: 20.51) were significantly higher than in the control treatment (ammonium: 4.93 nitrate: 5.06). The reason for reduced soil pH and EC can be the leaching of base cations followed by leaching of nitrate and an increased ammonium concentration in the soil. The reason for increased nitrate can be its addition as well as the production of nitrate in the presence of ammonium. In general, results showed that the nitrogen deposition treatments had destructive effects on soil chemical properties that decreased pH and EC, potassium and phosphorus and increased the total nitrogen, organic Carbon, ammonium and nitrate in the soil. Conclusion: Increased nitrogen at the early stages may be partly responsible for tree growth but, with the passage of time and the saturation of nitrogen in the soil and the occurrence of nitrate leaching as well as loss of soil fertility, conditions for the growth of plants would become unsuitable. Due to a lack of data on the effects of nitrogen deposition on soil properties, extensive studies about its effects on the soil chemical and biological properties, such as soil microbial and enzyme activities as well as soil respiration, is suggested.
Shahram Jafarnia; Seyed Mohammad Hojjati; Yahya Kooch
Volume 9, Issue 4 , July 2012
Abstract
In this study, a statistical survey of the mangrove habitat of Qeshm Island was carried out for better public recognition and its structure and the vegetative mangrove forest components as well as their relationship to the physical and chemical characteristics of soil and water were examined. In order ...
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In this study, a statistical survey of the mangrove habitat of Qeshm Island was carried out for better public recognition and its structure and the vegetative mangrove forest components as well as their relationship to the physical and chemical characteristics of soil and water were examined. In order to do this, six transects were chosen in three regions of mangrove with closed, medium, and low canopy density, respectively. In 60 sample plots, the vegetative parameters, tree density per hectare, canopy percentage, aerial root density and height, regeneration, and tree height were measured per unit area. In the center of each sample, fifteen physical and chemical soil and water parameters were measured. Finally, the relationship between the various vegetative characteristics at different cover densities and soil-water characteristic levels was studied using principal component analysis (PCA). The results of PCA on fifteen recorded environmental variables showed that the first and second principal components explain 86.63% and 13.36% of the evaluated parameter changes, respectively. Generally, the soil organic matter and clay percentage as well as the sodium level in areas with high densities of cover are considered to be factors impacting on the vegetative characteristics of Hara trees.
