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Investigation on the shape of the curve for responses of plant species to environmental gradients is one of the basic topics in the science of rangeland ecology. The objective of this study was investigation on the response of Bromus tomentellus and Festuca ovina species to some environmental variables using the generalized additive model (GAM) in the rangeland of Galandrood watershed in Mazandaran province. Towards this attempt, 153 quadrates of 1m2 along altitudinal gradient were taken. The sampling method was randomized-systematic. In the area sampled, presence of B. tomentellus and F.ovina, altitude, slope and aspect were recorded. Soil samples were taken from 0-20 cm in each quadrate. In each quadrate, soil properties including: pH, N, EC, organic carbon, the percentage of sand, silt and clay were measured. In order to study the shape of response curve in relation to the mentioned variables, GAM model was used with binomial distribution function. The data were analyzed by R ver.3.0.2 computer program. Results showed that altitude was the most important variable affecting the presence of B. tomentellus, While variables such as temperature and slope were the most important factors affecting the presence of F.ovina species. Clay and silt content in the soil were parameters that had significant negative impact on B. tomentellus and F.ovina species distribution. So, with an increase in clay and silt content of the soil, the possibility of the B. tomentellus and F.ovina presence were reduced.

Since Bromes tomentellus is one of the most important species in natural ecosystems in Iran both quantitatively and qualitatively, this research investigated decomposition process of Bromes tomentellus through studying dynamism of the main nutrient elements and decomposition rate of leaves and stems of the plantin a period of one year. The litter bag technique with size of 20×20 cm and 2 mm pores was used in this research. Each bag was filled with 5 g dried plant specimens. A totallof 54 bags with leaf, stem, and combination of leaf and stem were placed with three replications in Hosein Abad Research Station. Bags were taken at intervals of 60 days (6 times in a year). The amount of nutrients N, C, K, P, and C/N in leaves, stems, and the combination of leaves and stems were measured after each sampling. The results showed that the percentage of N in leaf was 1.02 which was 0.65 and 0.34 more in comparison with the nitrogen content of stem and the combination of leaf and stem, respectively. Also, annual decomposition constants of leaves, stems, leaves and stems of this species were 1.22, 0.95, and 1.88 respectively.

The effects of plant density and water stress on yield of Medicago sativa and Bromus tomentellus was studied. A greenhouse experiment was conducted at Isfahan University of Technology in 2013. The experiment included 18 treatments, three crop compositions (M.sativa, B. tomentellus or mixture of the two), two plant density levels, three watering regimes and four replicates, arranged in a completely randomized block design. Results showed that total yield of M. sativa mono-cropping was higher than mixed cropping and it was higher than B. tomentellus mono-cropping. Land Equivalent Ratio (LER) values were less than 1 for all mixed cropping treatments, indicated the interspecific competition in mixed cropping. The biomass production per plant decreased with increasing density, competition for resource utilization and water stress. Compare of above-ground and below-ground dry matter showed that M. sativa appeared to be more constrained by intraspecific than by interspecific competition, Conversely, B. tomentellus was more suppressed by interspecific competition exerted by M. sativa than by intraspecific competition. Relative competition intensity (RCI) values were positive for B. tomentellus and negative for M.sativa, implying that competitive ability of M.sativa was higher than B. tomentellus in mixed cropping .

Bromus tomentellus is one of the drought resistant species that has a relatively well developed in Esfahan province, therefore, in the present study some of the important factors that influence the distribution of this species are studied. In this study, 17 climatic variables from 43 synoptic and climatology stations were selected within and adjacent areas of Esfahan province which the stations managed by Weather Organization of Iran. To reduce the number of variables and determining effective factor was used factor analysis using by principal components analysis with varimax rotation, then the average factor scores in the habitat of this species and the areas without it were calculated and the spatial distribution of the factor scores were plotted in Surfer ver8. The results of the factor analysis identified three factors of precipitation, temperature and wind and sunshine hours. These factors are included 69.70%, 11.98% and 10.14%, respectively and 92% of the total variance of the data. Also, the results showed that both precipitation and cooling temperature are the important factors to presence of these species as dominant and following species and wind and sunshine hours has the least effect on it. Generally, the climate vegetative of Bromus tomentellus can be named in Isfahan province, semi-steppe vegetation region in Fereidan, Freydoonshahr, Semirom, Golpayegan, Khonsar, Meimeh up around the Shahreza and alpine steppe of Natanz and Kashan.

Three grass species, Agropyron desertorum (Agde) and Agropyron elongatum (Agel) and recently, Bromus tomentellus (Brto) are mainly used for range improvement as mixed seeding in semi-arid areas of Iran. Because there is little information about management of these grasses, this study was conducted at the Sisab Research Station in northern Iran to evaluate their responses to grazing management and annual precipitation. Four grazing management treatments were applied for three consecutive years, from 1999 to 2001: no grazing, and light (20-45% forage removal), moderate (45-65% forage removal) and heavy (65-80% forage removal) grazing by lambs and sheep. The fourth year was considered to be a rest from grazing. Data recorded up to fifth years from 1999-2003. The average herbage yield (HY) production across years of Agde (1357 kg/ha) and Agel (1250 kg/ha) was statistically similar, and higher than that of Brto (880 kg/ha). HY decreased with reduction in annual precipitation for all species, especially Agel. Plant number per unit area declined over the study period in all species. Three years of heavy grazing resulted in significant reduction in HY and/or plant number for Brto and Agde, but the rest year compensated for the negative effect of intensive grazing on dry matter production

Three grass species, Agropyron desertorum (Agde) and Agropyron elongatum (Agel) and recently, Bromus tomentellus (Brto) are mainly used for range improvement as mixed seeding in semi-arid areas of Iran. Because there is little information about management of these grasses, this study was conducted at the Sisab Research Station in northern Iran to evaluate their responses to grazing management and annual precipitation. Four grazing management treatments were applied for three consecutive years, from 1999 to 2001: no grazing, and light (20-45% forage removal), moderate (45-65% forage removal) and heavy (65-80% forage removal) grazing by lambs and sheep. The fourth year was considered to be a rest from grazing. Data recorded up to fifth years from 1999-2003. The average herbage yield (HY) production across years of Agde (1357 kg/ha) and Agel (1250 kg/ha) was statistically similar, and higher than that of Brto (880 kg/ha). HY decreased with reduction in annual precipitation for all species, especially Agel. Plant number per unit area declined over the study period in all species. Three years of heavy grazing resulted in significant reduction in HY and/or plant number for Brto and Agde, but the rest year compensated for the negative effect of intensive grazing on dry matter production. [ABSTRACT FROM AUTHOR]

Seed priming is known as a seed treatment which improves seed performance under environmental conditions. Objective of this study was to evaluate the effects of different priming treatments on seed germination behaviour of two genotypes of Bromus under laboratory conditions to find out the most effective priming treatment. Seeds were treated with the following seed-soaking media: (i) unsoaked seed (control); (ii) hydropriming with distilled water for 4, 8, 12 and 16 hours, (iii) osmopriming treatments with PEG 6000 for Bromus tomentellus were -0.6, -0.8, -1.0 and -1.2 MPa osmotic potentials with duration of 12, 24 and 36 hours and for Bromus inermis osmoticpotentials were the same as B. tomentellus but duration of priming treatments was soaking seeds for 12, 24, 36 and 48 hours. Seeds of both genotypes were placed in liquid priming media at 25°C. Priming treatments significantly affected germination vigour of both genotypes. The response of both genotypes to different priming techniques approximately was similar. Osmopriming treatment (-0.6 MPa and 12 h) increased final germination percentage of B. tomentellus. Priming treatments increased coleoptile length significantly comparing to control but hydropriming for 4 h exhibited longer coleoptile than others. Higher vigour index was observed in hydropriming for 12 h but this difference was not significant with osmoprime treatment (12 h-0.6 Mpa). B. inermis produced more germinated seeds and vigourous seedlings than B. tomentellus but germination rate was higher in B. tomentellus. [ABSTRACT FROM AUTHOR]

Neotyphodium species occur as endophytic fungi in cool-season grasses around the world. The beneficial aspects of grass– Neotyphodium associations have provoked researchers to look for a novel association in plant species where this symbiotum has not been reported. We surveyed Russian bromegrass ( Bromus tomentellus Boiss.) accessions from a germplasm collection for the presence of Neotyphodium spp. fungi and determined levels of endophyte infection in B. tomentellus populations in native rangelands of Iran. Among 50 collected accessions, symbiotic fungi were detected in 45 accessions without any symptoms of choke disease on host plants. In culture medium, fast-growing endophytes appeared from seeds after 7–14 days. Plants grown from seed collections were 80–100% infected. Based on morphological characteristics and PCR analysis, we concluded that this fungus is a member of the Neotyphodium group of endophytic fungi. Lack of apparent toxicity to grazing animals suggests a place for endophyte-infected B. tomentellus in rangeland renovation, providing this infected grass exhibits increased tolerance to abiotic stresses. [ABSTRACT FROM AUTHOR]

This research was carried out to assessing the potential of Bromus tomentellus for phytoremediation with biochar and municipal waste compost amendments to improving the clean-up efficiency of soils contaminated with chromium (Cr) and zinc (Zn). Soil amendment was added to contaminated soil in three levels (%0: Control; without organic fertilizer, biochar and compost 1%, biochar and compost 2%). It also determines the applicability of artificial neural network (ANN) in the modeling of the extraction process. The physiochemical properties of the contaminated soil, including pH, Electrical Conductivity (ECe), Cation Exchange Capacity (CEC) and Sodium Adsorption Ratio (SAR) were determined. After validation of the applied artificial neural network, the effect of municipal waste compost and biochar treatment on the absorption of heavy metals in different parts of the plant was investigated. Also, the range of adding amending factors to the soil through the neural network increased from 2% in experimental data to 5% in predicting data. The neural network was taught for heavy metals in soil and plant, so the amount of Correlation coefficient (R2) value in most cases was higher than 0.9 and close to 1 which means the Group Method of Data Handling (GMDH) and artificial neural network was usable for over-predicting data. The results indicated that by adding compost percentage, the absorption of Zn is also increased. The highest concentration of Zn (274.82 mg/kg) and Cr (26.66 mg/kg) was observed by adding 0.8% compost and 0.52% biochar, respectively. The maximum Cr concentration for compost (25.19 mg/kg) was detected by adding 1% compost. • Application of urban waste compost and biochar are more efficient on the potential of Bromus tomentellus to accumulate chromium and zinc • Biochar has a potential of improveing soil properties • The highest concentrations of Zn was observed by adding 0.8% compost • The highest Cr concentration for compost was detected by adding 1% compost [ABSTRACT FROM AUTHOR]