mahboobeh abasi; Mohammad Jafari; Ali Tavili; Hamed Rafiee; Shahram Khalighi
Volume 30, Issue 1 , April 2023, , Pages 164-179
Amir Ghorbankhani; Hossein Arzani; Ali Tavili; Javad Motamedi
Volume 29, Issue 1 , February 2022, , Pages 1-10
Abstract
Salsola laricina is one of the main elements of vegetation communities in the steppe rangelands of the dryland region, which protects it from disturbances and provides conditions that can preserve its ability to rehabilitate after chest, is one of the basic requirements of rangeland management in such ...
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Salsola laricina is one of the main elements of vegetation communities in the steppe rangelands of the dryland region, which protects it from disturbances and provides conditions that can preserve its ability to rehabilitate after chest, is one of the basic requirements of rangeland management in such fields. Therefore, in the present study, the variability of structural and functional traits and morphological characteristics and seed germination were tested under supportive grazing. For this purpose, by establishing a sampling system inside and outside of the 10 year old Khoshkerood detention, the vegetation cover and structural and functional traits of Salsola laricina species, such as crown cover, density and forage production in the field were measured. Seed of healthy and healthy rootstocks, morphological characteristics and seed germination, such as; 1000 seed weight, germination percentage, germination rate, root length, stem, seedling, and finally vigor index (straw) Seed) was measured in laboratory conditions. The results showed that the values of structural and functional traits, inside the enclosure, are more than outside the enclosure. In this regard, the percentage of crown cover, density, and amount of production of Salsola laricina species were respectively in the enclosure relative to the outcrop, 5.46 and 3.6%, 21600 and 17000 bases per hectare and 161.4 and 12.71 kg respectively hectare. The average of morphological and germination characteristics of the seeds collected from the intruder was also greater than the outside grazing. So that the highest index of seed vigor as a sum of outcomes of morphological and germinating properties in inoculated and outcroped seeds is 389.88 and 1037.37, respectively. The increase of these values in the enclosure relative to the outcrop; indicates the effect of supportive grazing on the improvement of structural and functional characteristics and the morphological and seed germination characteristics of rangeland species in vulnerable ecosystems in arid areas.
Ali Tavili; Hamed Eskandari Damaneh
Volume 28, Issue 1 , April 2021, , Pages 93-105
Abstract
Seed germination is usually the most critical factor in determining the success or failure of plant establishment. The most important environmental factors affecting germination, establishment, and growth of plants are temperature and humidity, which have significant effects on germination characteristics ...
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Seed germination is usually the most critical factor in determining the success or failure of plant establishment. The most important environmental factors affecting germination, establishment, and growth of plants are temperature and humidity, which have significant effects on germination characteristics such as germination percentage and rate. For this purpose, to determine the cardinal temperatures of seed germination in Ziziphus spina-christi, in vitro experiment, the germination characteristics of the seeds of this plant at different temperatures were evaluated in a completely randomized design with four replications. Germination response was assessed at the constant temperatures of 5, 10, 15, 20, 25, 30, 35, 40, and 45°C. The cardinal temperatures for the germination of Ziziphus spina-christi seeds were fitted using germination rate and by three models including the beta, segmented, and dent-like models. To select the superior model and measure the accuracy of the model in describing the germination rate of Ziziphus spina-christi seeds for temperature, the statistics of root mean square (RMSE) and coefficient of determination (R2) were used. Accordingly, a higher R2 and a lower RMSE represent a closer correlation of the model with reality. Based on the results, these statistics were better for the segmented model than the other models, so that they were 0.0004 and 98% for this model, respectively. Therefore, based on the segmented model, which was known as the superior model, the basal temperature, the optimum and maximum germination rate of this plant were calculated to be 8.6, 34.3 and 49 ° C, respectively. Then, the response of germination and seedling growth of Ziziphus was explored in another experiment to different levels of salinity and drought stresses at the optimum temperature. In this experiment, the seed germination was studied at four levels of salinity and drought stresses with osmotic potentials of 0, -2, -4, -6, -8, and -10 bars. The results of this experiment showed that salinity and drought stress reduced the germination percentage and rate of Ziziphus spina-christi seeds. Germination percentage for control was 97% while in -10 bar salinity and drought stress was 16% and 0, respectively. In addition, compared to drought, seed germination showed more sensitivity to salinity stress.
Mohammadreza Rahdari; Hasan Ahmadi; Ali Tavili; Mohammad Jafari; Aliakbar Nazari Samani; mohammad khosroshahi; Shahrooz Sharifi
Volume 26, Issue 1 , June 2019, , Pages 226-240
Abstract
Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway ...
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Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway (178 km). For this reason, hourly wind speed and direction data were analyzed. Annual wind roses showed that West and Northwest winds were predominantly about 40%, 50%, 42% and 57% at the stations of Tehran, Shahriyar, Qom, and Imam Khomeini airport, respectively. The highest amount of sand drift potential was at the Imam Airport station (DP= 574, UDI=0.8) in the west and its lowest value was at Qom station (DP= 109, UDI= 0.47) in the south of the region. The drift potential (DP) for aeolian deposits was generally high (DP >400) in the Garmsar (DP= 481), Salafchegan (DP= 485), Saveh (DP= 552) and Imam Khomini airport (DP=574) climatological stations. DP was relatively moderate (200>DP>400) at the Shariyar and Kahak stations in the northwest and south of study area, respectively; and weak (DP<200) in the Tehran and Qom climatological stations. There was an increasing trend in the transport of sand when moving from Namakzar railway station to the Imam Khomeini railway station. Also field evaluations indicated the sensitivity of the Separ Rostam-Namakzar block to entry of sand, which was 21.3 kilometers long. Finally, it is suggested to railway directors of the Islamic Republic of Iran to proceed with the assessment of sand drift potential near railways station for control of sand deposition.
reza Hasanpouri; Ali Tavili; seyed akbar javadi
Volume 23, Issue 4 , March 2017, , Pages 800-809
Abstract
Identification of effective environmental factors in distribution and establishment of plant species plays an important role in rangeland ecosystems management. The purpose of this study was investigation of reasons for plant species distribution and relationship between index species in Khorramabad ...
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Identification of effective environmental factors in distribution and establishment of plant species plays an important role in rangeland ecosystems management. The purpose of this study was investigation of reasons for plant species distribution and relationship between index species in Khorramabad rangelands and physical and chemical properties of soil. At preliminary inspection, vegetation types were separated and the key area of each type was recognized. Four vegetation types were identified as follows: Agropyron libanoticum-Acantholimon bromifolium ،Hordeum glaucum-Taeniatherum crinitum، Astragalus adscendens-Agropyron trichophorum andAstragalus adscendens-Daphne mucronata. The size and number of sampling plots were calculated to be 4 square meters with minimal area method, and 160 based on the statistical formula, respectively. Sampling method in each vegetation type was randomize-systematic, so that, in each plot, vegetation factors were measured, then at the beginning and end of each transect a profile was dug and some physical and chemical properties of soil were measured. Vegetation ordination was done by CCA method and results showed that organic matter, nitrogen, phosphorus, potassium and pH were the most important factors affecting Daphne mucronata distribution. The distribution of Agropyron libanoticum and Acantholimon bromifolium were affected by potassium, soil texture, and EC. As well, soil texture and lime had a decisive role in distribution of Taeniatherum crinitum, Hordeum glaucum, Astragalus adscendens and Agropyron trichophorum.
Azin Jafarian; Mohammad Jafari; علی طویلی
Volume 21, Issue 1 , June 2014, , Pages 51-61
Abstract
Ecological effects of Haloxylon plantation on natural vegetation and soil properties were investigated in this study. For this purpose, three regions with 1 to 5-year-old, 5 to 10-year-old and over 20-year-old Haloxylon (Haloxylon persicum) and a control area for each region were determined. Vegetation ...
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Ecological effects of Haloxylon plantation on natural vegetation and soil properties were investigated in this study. For this purpose, three regions with 1 to 5-year-old, 5 to 10-year-old and over 20-year-old Haloxylon (Haloxylon persicum) and a control area for each region were determined. Vegetation sampling was conducted along a 300-meter transect to record crown cover percentage, density, production, litter, gravel ،bare soil ،species diversity and dominant species. In addition, soil sampling was performed at depths of 0-30 and 30-90 cm to measure soil properties including EC, pH, percentage of organic carbon, soluble calcium, magnesium and sodium, and silt, clay and gravel percentage. The study was performed through random-systematic sampling. Data were analyzed using independent t-test in SPSS software. Results indicated that Haloxylon plantation led to increase in percentage of crown cover, litter, and standing crop production. It also caused improvement in species composition, condition and trend as compared to the control area. Plantation of Haloxylon with different ages affected and increased soil electrical conductivity.
Ali Tavili; Mojtaba Janat rostami; Khadejeh Ebrahimi Dorcheh
Volume 16, Issue 3 , December 2009, , Pages 409-418
Abstract
According to importance of Salsola rigida in arid and semi arid regions, also due to Artemisia sieberi allelopathic property, this research was carried out to find whether or not Sa. rigida is sensitive against Ar. sieberi allelochemicals in germination stage when they are planting with together. For ...
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According to importance of Salsola rigida in arid and semi arid regions, also due to Artemisia sieberi allelopathic property, this research was carried out to find whether or not Sa. rigida is sensitive against Ar. sieberi allelochemicals in germination stage when they are planting with together. For this purpose, Sa. rigida seeds were taken from Pakan Bazr Cooperation in Isfahan. Aerial parts of Ar. sieberi were gathered from Jafarieh region in Qom province, dried and powdered. They were mixed with distilled water in a ratio of 1:3 (one part Sa. rigida powder, 3 parts distilled water). Based on standard methods, extracts with different concentrations were prepared. Sa. rigida seeds were put in Petri dishes and watered with different concentrations of the prepared extracts. Experiment was done in a completely randomized design with 4 treatments (0, 25, 50 and 100 percent extractions) and 4 replications. Understudy germination properties were Final Germination percentage (FG), Rate of Germination (RG), Mean period of Final Germination (MPFG) and Percentage of Inhibition (PI). Duration of experiment was 13 days. Results based on statistical analysis revealed that there was significant difference between FG, MPFG, and PI under different extract concentrations effects (P<1%) while for RG difference was significant at 5% probability. Totally, it is concluded that Sa. rigida could be affected by Ar. sieberi allelopathic property in germination stage.