Shiraz University Iran Agricultural Research 1013-9885 37 1 2018 06 01 Morpho-phenology and chromosome number of Iranian Bromus danthoniae Trin. genotypes 57 66 4718 10.22099/iar.2018.4718 EN M. Rezaei Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan I. R. Iran A. Arzani Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan I. R. Iran G. Saeidi Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan I. R. Iran Journal Article 2017 06 08 <em>Bromus danthoniae </em>Trin. is an annual grass species which grows mainly on dry grassy rocky mountain slopes and grassy steppe, and is grazed by many herbivores and recognized as a useful pasture plant. The chromosome number, morphological and anatomical traits of 82 genotypes of <em>B. danthoniae</em> belonging to three sub-taxa were investigated. Twenty-seven quantitative and 20 qualitative morphological traits were evaluated. The results of analysis of variance showed that <em>B. danthoniae</em> genotypes varied significantly for all quantitatively tested traits. Based on cluster analysis, the genotypes were divided into four groups which mostly corresponded to their subspecies identities. According to correlation analysis, lemma length had strong positive correlations with other traits such as awn length (r=0.55**), lemma width (r=0.72**) and caryopsis length (r=0.84**). In addition, lemma width was significantly correlated with the traits like floret number per spikelet (r=0.47**) and caryopsis length (r=0.58**). Based on factor analysis, the first three factors encompass about 51% of total variation. Overall, lemma length and lemma width were the two reliable traits for morphological investigations in this species. The results of chromosome counting showed that <em>B. danthoniae</em> subsp. <em>danthoniae </em>and<em> B. danthoniae </em>var.<em>lanuginusos</em> Roshev. were diploid (2n=2x=14) whereas <em>B. danthoniae</em> subsp. <em>pseudodanthoniae</em> (Drobov) H. Scholz was tetraploid (2n=4x=28). The results of leaf surface anatomy showed that tetraploid genotypes had larger stomata but lower stomatal density than the diploid ones, thus a comprehensive relationship between genome size and guard cell size cannot be ruled out as a plausible explanation for differentiating the ploidy levels. The high morphological variations among the <em>B. danthoniae </em>genotypes explain the habitat distribution of this species and enable us to incorporate this knowledge into practice by exploiting the variation for improvement of pasture production. https://iar.shirazu.ac.ir/article_4718_e7b19e074503aa75cded78902cdd10c8.pdf