Providing information about range plant species, to be used as the main basis for managing rangelands, necessitates studying their ecological behavior and relationship with biotic and abiotic components of rangeland ecosystems. In rangeland ecology, this type of studies is considered as autecology of range plant species. This research was conducted to study autecology of two range plant species of Bromus tomentosus and Agropyron pectiniforme in Mazandaran Province. Site characteristics, including topography, climate, soil, and accompanied plant species were determined. For each of the two species, phenology, root system, and their way of presence in the vegetation cover of rangeland ecosystem were examined. The results showed that Agropyron pectiniforme grows in locations with an elevation range of 1200-3000 m above sea level. Soil texture of growing areas is loamy or silty-loam. Soil electrical conductivity (EC) is 0.45-0.94ds/m, while soil pH is 7 to 7.86. Annual precipitation at its ecological habitats is 320-653 mm; and average annual temperature is 7.2-16.2 degree of centigrade. Canopy cover and frequency for this species were 7.22% and 36.6%, respectively. The root system of this range plant species is fibrous and distributes among soil particles down to the depth of 21 centimeter. Vegetative growth stage of this species starts in late March and ends in late April. Its flowering stage is from early May until early June, and seed ripening is in late June. The results of study on Bromus tomentosus showed that this plant grows in locations with an elevation range of 2300-3300 m above sea level. Soil texture of growing areas is loamy or silty-loam. Soil electrical conductivity (EC) is 0.40-0.72ds/m while soil pH is 7.21 to 7.47. Annual precipitation at its ecological habitats is 510-653 mm; and average annual temperature is 7.2 degree of centigrade. Canopy cover and frequency for this species were 16.75% and 5.73%, respectively. The root system of this species is fibrous and distributes among soil particles down to the depth of 27 centimeter. Its vegetative growth stage starts in early April and ends in early May. Flowering stage of this range plant is from mid May until mid June, and seed ripening occurs in mid July. Ecological characteristics of these two range plant species need to be considered in management programs of related rangeland ecosystems.

The evaluation of utilization of key species is cornerstone of decision-making in rangeland management. Measuring utilization is essential for regulating grazing intensity, grazing pressure and distribution of animals. utilization of two key grass species of Dactylis glomerata and Bromus tomentosus, as two important rangeland species is determined using height-weight relationship. The research is done in two vegetative periods of prior to flowering and flowering stages in two region of grazing land and exclosure by 32 transects of 100-meter length. To do so, the height of species was measured and cut at 1-cm above soil surface and weighted freshly. The samples are clumped and moved to the laboratory and oven dried at 65° c after separating litter divisions Then, the whole individual plants were weighted and cut in 5-cm intervals and each part was re-weighted and recorded separately for each species. Height-weight relationships were analyzed by different regression models in SPSS v. 18 software. Result shows that sigmoid model significantly illustrate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0. 994 and 0. 997 at prior to flowering stage in the exclouser respectively. Similarly, sigmoid model also elucidate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0. 975 and 0. 998 at the flowering stage in the exclouser, respectively. The sigmoid model also best fitted for depicting height-weight relationship of both species at prior to flowering stage in grazing land for both species with R2=0. 996, too.

Twelve populations of Bromus tomentellus which were collected from different parts of the country were studied for various morphologic and karyotypic characteristics. The recorded data were analysed using appropriate model of analysis of variance.Obtaining confident result of differences between the populations for the morphologic and karyotypic characteristics, complementary analysis was performed on the data. The populations were classified for the different karyotypic characteristics and correlations between all combinations of the populations were estimated based on the karyotypic characteristics. Cluster analysis was used to classify the populations based on the morphological and karyotypic characteristics. The least and the most similar populations were identified based on the two sets of the data. A number of statistics were estimated for assymetry assessment of the karyotypes.Regarding the results of analysis of variance on the morphologic data, the populations were significantly different for all of the studied characters. The populations, their chromosomes and their interactions were significantly different for most of the karyotypic attributes. The populations were highly correlated based on the total length of the chromosomes but weak correlations were observed based on the long arm to short arm ratio for some combinations of the populations. Using cluster analysis results, the most distant populations based on the karyotypic characters which may cause infertility in their progenies due to incompatibility were recognized. The most distant populations based on their morphologic characters which may produce enough genetic variation in breeding projects were also identified.

This article is a taxonomic review after Flora Iranica concerning some species of Bromus sect. Bromus. Comparing the holotype, isotype and paratype of B. pseudobrachystachys with the lectotype of B. brachystachys and also reexamination of three Iranian and Iraqi herbarium sheets putatively determined under the latter’s name showed all belong to the former. B. racemosus, B. arvensis and B. secalinus are confirmed to occur in Iran. Despite B. tigridis was identified from Turkey based on the sheet Sorger & Buchner 82-62-54, the Iranian specimen was identified as B. racemosus. Furthermore, a new record of this section i.e., B. macrocladus is reported here from mountains of Razi village (W Khoy, NW Iran).

Bromus catharticus Vahl and Bromus danthoniae Trin. var. uniaristatus Melderis are reported as two new records from Iran. Exact localitis based on herbarium specimens are given and geographical distribution of the species are explained.

Autecological study of range plant species to provide basic knowledge for managing rangeland ecosystems is eminently important. This study was conducted to furnish some information about autecological function of two range plant species of Bromus cappadocicus and Bromus stenostachyus in Mazanderan Province of Iran. Some topographic, climatic, and edaphic aspects, as well as the boundaries, of the ecological habitats of these species were delineated. Phenological stages, root system, and the way of presence of each of these two species in the vegetation assemblage were determined. The names of other species accompanied with each of these two species were listed. The results show that the habitats of Bromus cappadocicus in Mazanderan Province are very limited. This species was observed in some scattered patches at slopes of %5-60 and altitudes of 2550-3100 m above sea level, mainly in western and central sections of the province. Average annual rainfall at these habitats is 400-500 mm. Tests of soil texture indicates that this range plant species grows in loamy and loamy silt soils. In the main section of its habitat, at the altitude of 3100 m above sea level, vegetative growth of this plant starts in early April. Its flowering stage starts in mid May; and the seeds ripen in mid June. The root system of this species is fibrous and distributed among particles of shallow soils. Ecological habitats of Bromus stenostachyus are at altitudes of 1500-4000 m above sea level and slopes of %10-70, in central parts of Elborz Mountain in Mazanderan Province. At most of its habitats, this species was observed as first dominant, second dominant, or third dominant species of the vegetation. At the elevations of 3000-4000 m above sea level, however, it grows in scattered patches. Annual rainfall at these areas is 400-500 mm. This range plant prefers loamy and loamy silt soils too. At the altitude of 3100 m above sea level, vegetative growth of this plant starts in early to mid May. Its flowering stage is in mid to late June; and the seed ripening stage is in early to mid July. The root system of this species is fibrous and distributed among particles of shallow soils. The findings of this study suggest that considering the autecological characteristics of these two species is highly essential for managing of such fragile rangeland ecosystems.

Bromus genus is one of the most important rangeland plants which have distributed in wide range of natural areas in our country. The interspecific relationship were evaluated in 45 diploid populations of two sections of Bromus and Genea, with 5 populations of Lolium multiflorum species based on karyotype characteristics. For each population five mitotic cells in metaphase stage were prepared from meristematic cells of root tips in newly germinated seeds. The total length, short arm and long arm length of chromosomes were measured. The centromer index, arm ratio, relative chromatin value, intrachromosomal and interchromosomal asymmetry index and total form percentage of chromosomes were calculated. The karyotypic asymmetry and types of chromosomes were determined. Variance analysis were showed a significant variation (P<0.01) between species and among populations. The populations had a symmetric karyotype which, were placed in A1 and A2 Stebbins’s classes and had a metacentric chromosomes and a few sub-metacentric chromosomes. The species of two sections were separated based on principal component and cluster analysis. The Karyotypic evolution for Bromus section was more from the chromatin value and for Genea section was further by increasing the asymmetry within and between chromosomes. B. briziformis Fisch. & C. A. Mey and B. squarrosus L. had the most karyotypic evolution and B. scoparius L. and B. danthoniae Trin. ex C. A. Mey. had the least karyotypic evolution in Bromus section. B. japonicus Thunb and B. rechingeri Melderis were placed between the two previous groups. B. tectorum L. were showed a karyotypic evolution more than B. sterilis L. and B. sericeus Drobow. in Genea section.

Bromus is one of the most important genus in the rangelands of which several species have covered a vast areas of our country. Different species of the genus have not been paid enough attention for genetic and cytogenetic variation whereas, information on karyotypic characteristics and ploidy levels are of primary requirements of breeding projects of each plant species. For these reasons in the current study several species of Bromus were studied for karyotypic characteristics by studying metaphase chromosomes in mitotic meristem cells. In order to prepare mitotic cells, fresh grown root tip meristems of germinated seeds were used. Bromonaphtaline, Farmer fixative and Hematoxiline were used for pretreatment, fixation and staining, respectively. Six species of the genus were studied in this research. Different ploidy levels were observed between the different populations and species, which were mainly a multiplication of seven. This variation in ploidy level particularly within the species could cause morphological variation and resultantly better stability of the species. It could also provide the suitable opportunity for utilizing the variation in breeding and developing Bromus cultivars in the country. In the future studies the populations have to be studied for karyotype asymmetry to find relationship between the populations in order to use their potentials in breeding projects.

Bromus tomentellus is one of the important and valuable grass species for forage production. In order to study the seed and dry forage yield and drought tolerance, eleven genotypes of B. tomentellus were evaluated in two separate experiments under irrigated and rainfed conditions using randomized complete block design with three replications in Agricultural Research Station of Broujerd, Iran, during 2005-2006. Using principal component analysis of drought resistance indices as mean productivity (MP), tolerance index (TOL), stress susceptibility index (SSI), stress tolerance index (STI) and geometric mean productivity (GMP) and seed yield and  forage yield in irrigated (Yn) and rainfed (Ys) conditions, genotypes were distributed in two-dimensional diagram based on of the first two principal components. Genotype 3752M with average seed yield of 265 kgha-1 and genotypes 587M, 587P7, 587P12 and 587P3 with average forage yield of 1680.3 to 1897 kgha-1 exhibited suitable drought tolerance.