Robab Bagherian; Kiomars Sefidi; Farshad Keivan Behjou; Ali Ashraf Soltani; Behzad Behtari
Volume 25, Issue 1 , April 2018, , Pages 183-190
Abstract
To evaluate the effects of grazing on some physical and chemical properties of soil, in the summer rangelands of southern slopes of Sabalan, three regions with different grazing intensity were selected after field observation and 27 soil samples were randomly taken along three 200-m transects. Soil samples ...
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To evaluate the effects of grazing on some physical and chemical properties of soil, in the summer rangelands of southern slopes of Sabalan, three regions with different grazing intensity were selected after field observation and 27 soil samples were randomly taken along three 200-m transects. Soil samples were taken from the depths of 15-0, 30-15 and 45-30 cm and transported to laboratory and soil properties such as texture, organic matter, organic carbon, phosphorus, potassium, EC and pH were measured. Analysis of variance and mean comparison were made using Duncan's test. Results showed that no significant difference was found for soil pH and phosphorus among the grazing intensity treatments and soil depths; however, significant differences were observed for other variables. The results showed that organic matter content decreased with increasing of grazing intensity and the lowest content was recorded for the 30-45 cm soil depth in the heavy grazing area. According to the results of this research it can be concluded that soil structure is degraded with increased grazing intensity; therefore, a balanced grazing need to be taken into account in summer rangelands to prevent soil degradation.
Hadi Radnezhad; behzad Behtari; Ali Asghar naghipour Borj; Shole Haj Agfha Memar
Volume 23, Issue 4 , March 2017, , Pages 760-771
Abstract
Plant growth-promoting rhizobacteria are a subset of bacteria, accumulating on the root and rhizosphere. One of the seed priming methods is the use of microorganisms in seed inoculation, known as biopriming. The use of these microorganisms in seed inoculation leads to increased plant performance, especially ...
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Plant growth-promoting rhizobacteria are a subset of bacteria, accumulating on the root and rhizosphere. One of the seed priming methods is the use of microorganisms in seed inoculation, known as biopriming. The use of these microorganisms in seed inoculation leads to increased plant performance, especially if the microorganisms are symbiotic in the root zone of the plants. This study was aimed to investigate the effects of biopriming with Azospirillum and Azotobacter on drought resistance in fescue under greenhouse conditions. Osmotic potential at four levels was applied on the Fescue seeds using polyethylene glycol for 2 and 4 days as priming treatment along with inoculation with rhizobacteria. Drought stress was applied during the plant growth based on field capacity at four levels. The results showed that biopriming treatments caused improved performance and increased drought resistance compared to the control. The study showed that both Azospirillum and Azotobacter increased the performance significantly compared to the control. Generally, Azotobacter showed relatively better performance than Azospirillum. However, the Azotobacter treatments at 2 and 0.5 MPa for 2 days can be considered as a superior treatment in fescue as compared with other treatments.
Shole Haj agha Memar; Farshad Keivan Behjou; Kiomars sefidi; Behzad Behtari
Volume 23, Issue 2 , September 2016, , Pages 343-330
Abstract
The aim of this study was to investigate the impact of ecosystem change on emissions and carbon mineralization rate in Fandoghloo region. Soil sampling was performed at three depths (0-30 cm) from the grazing rangeland ecosystem, degraded rangeland ecosystem, and agricultural, ...
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The aim of this study was to investigate the impact of ecosystem change on emissions and carbon mineralization rate in Fandoghloo region. Soil sampling was performed at three depths (0-30 cm) from the grazing rangeland ecosystem, degraded rangeland ecosystem, and agricultural, ecosystem. Carbon dioxide emissions were measured during incubation with alkali absorption method. The highest and lowest emissions of carbon dioxide and carbon mineralization rate were obtained in the grazing rangeland ecosystem (0.968 mg CO2 g-1 soil and 0.00314 mol C kg-1 soil d-1), and the degraded rangeland ecosystem (4693 mg CO2 g-1 soil, and 0.0015mol C kg-1 soil d-1), respectively, showing a significant difference with other ecosystems at different depth levels. According to the results, significant differences were found for the activity of microorganisms in decomposition of organic matter in the study ecosystems. The dynamics of vegetation and returned fine roots caused high emissions of CO2 in soil of grazing rangeland ecosystem. In the agricultural ecosystem, due to the relatively wet conditions and failure to return organic matter to the soil, the decomposition of inaccessible organic matter caused to decreased soil organic matter and low carbon dioxide emissions.
Behzad Behtari; Ghasemali Dianati Tilaki; Farzaneh Gholami
Volume 18, Issue 4 , September 2012, , Pages 526-536
Abstract
Salt and osmotic stresses are responsible for both inhibition or delayed seed germination and seedling establishment. Salts may affect seed germination by either restricting the supply of water (an osmotic effect) or causing injuries through involvement of their ions into the metabolic processes (ionic ...
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Salt and osmotic stresses are responsible for both inhibition or delayed seed germination and seedling establishment. Salts may affect seed germination by either restricting the supply of water (an osmotic effect) or causing injuries through involvement of their ions into the metabolic processes (ionic effect). The aim of the study was to determine the effect of salt and osmotic stresses on Agropyron cristatum and Agropyron elongatum seeds. In this respect, iso-osmotic solutions of sodium chloride (NaCl) and Polyethylene glycol 6000 (PEG 6000) under osmotic stress levels of (0, 4 and 8 bars) were applied to induce osmotic and ionic effects. The applied experimental design was completely randomized design with a three-factor factorial (2×2×3) arrangement in three replications and 50 seeds per replication. Germination percentage, germination rate, shoot length and vigor index showed significant reduction due to higher osmotic tensions on both Agropyron species. Only root length had no statistically significant difference between stress levels 0 and 4 bars. Iso-osmotic solutions of NaCl and PEG 6000 in A. cristatum did not show statistically significant difference, but in the case of A. elongatum significant differences were observed between these two iso- osmotic solutions. This study showed that PEG 6000 as an osmotic agent of salinity had more inhibition effect rather than ionic effect of Nacl. However, the toxicity of ionic effects was raised by increase of osmotic stress levels. This study showed that the tolerance of A. elongatum against salinity was more than A. cristatum species.
Ghasemali Dianati-Tilaki; Bahman Shakarami; Masoud Tabari; Behzad Behtari
Volume 18, Issue 3 , September 2011, , Pages 452-462
Abstract
Salinity is one of the most important abiotic stresses that negatively affects the seed germination and growth of seedlings in plants. NaCl priming is of techniques to improve the seed performance and could increase germination percentage, growth of the seedlings and the mean time of seed germination ...
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Salinity is one of the most important abiotic stresses that negatively affects the seed germination and growth of seedlings in plants. NaCl priming is of techniques to improve the seed performance and could increase germination percentage, growth of the seedlings and the mean time of seed germination under salinity conditions. This study was conducted to improve the seed performance of Festuca ovina under salinity stress conditions. A factorial experiment was applied based upon a completely randomized design with three replications (50 seeds per Petri dish). The effects of priming with three optimized dose (15, 30 and 45 dS/m) of NaCl solution for 24 h at 22±2 oC under dark conditions were assessed for improving seed traits of sheep fescue. NaCl primed Seeds were also examined at different salinity levels) 0, 5, 10, 15 and 20 dS/m). Germination percentage and mean germination time were significantly affected by interaction of salinity and priming. Root length, shoot length and vigor index was not affected significantly by priming treatments in all salinity levels. Germination percentage of primed seeds especially in high salinity levels (15 and 20 dS/m) was greater than to non-primed seeds. The results showed that NaCl priming (especially at 45 dS/m for 24 h) in high salinity levels could increase the seed yield of Festuca ovina in terms of seed germination.