DefinePK

Abstract

The genus Bromus L. belongs to tribe Bromeae Poaceae, family. The taxon includes about 160 annual and perennial species distributed all over the world. It has important rangeland plant species in Iran, which are placed in 6 sections. Nine populations of three Bromus species B. danthoniea Three populations, B. sterilis three populations and B. tectorum three populations were selected based on their morphological characteristics to investigate their karyotypes. Preparations were made using fresh grown root tips. Saturated -bromonaphtaline, formaldehyde and chromium trioxide 11, 1 N NaOH and hematoxiline were used for pre- treatment, fixative, hydrolyser and chromosome staining agent, respectively. The chromosomal studies were done using photomicroscope equipped with micrometer. Karyological data such as long arm, short arm and total length were recorded on all chromosomes of 5 well-prepared cells at metaphase stage containing a complete set of chromosomes. Finally, Pearson correlation coefficient was estimated for all paired combinations of the karyotypic characteristics to investigate their inter-relationships. Stebbins table was used for determining evolutionary state and karyotypic symmetry of the studied genotypes. All populations had mainly metacentric type chromosomes. Bromus danthoniea was placed in A1 and had the highest values of inter-asymmetry chromosomal index. It had the lowest TF. Based on Stebbins table all species were placed in class 1A and primitive evolutionary state.