Hossein Mirzaie-Nodoushan - Research Institute of Forests and Rangelands, P. O. Box ۱۳۱۸۵ - ۱۱۶, Tehran, Iran.
Ali-Reza Zebarjadi - Agricultural College, Tarbiat Modarres University, Tehran, Iran.
Ghasem Karimzadeh - Agricultural College, Tarbiat Modarres University, Tehran, Iran.

Twelve populations of Bromus tomentellus collected from different parts of Iran were surveyed for karyotypic characteristics. The data were analysed using a factorial model of analysis of variance. After a confident result of differences between populations for the characters, complementary analysis was performed on the data. The populations were classified for the karyotypic characteristics and correlations between all combinations of the populations were estimated based on the total chromosome length and long arms of the chromosomes. Using principle components analysis the most variable karyotypic characters were identified. The principle components which contained the most amounts of existing variation of the data were also recognized. The two main components were used to produce a scatter plot of the populations. Cluster analysis was used to classify the populations based on the chromosomes total length and all of the measured characters. Regarding the karyotypic characteristics the least and the most similar populations were identified. Several statistics were estimated for assessment of asymmetry of the karyotypes. Regarding the results of the analysis of variance, the populations, chromosomes and their interactions were significantly different for most of the studied characters. The populations were highly correlated based on the total length of the chromosomes and L/S ratio but some weak correlations were also observed between some combinations of the populations. In principle components analysis, total length of the chromosomes and long arm length had the most influence on the first component, which in turn contained more than ۹۰% of the existing variation in the data. Cluster analysis on both of the total length of chromosomes and all of the recorded attributes produced a similar grouping. The most distant populations based on their karyotypes, which may produce infertile progenies in breeding programs were also identified.

Bromus tomentellus, Karyotype, Mitosis, multivariate analysis