MEIOTIC STUDIES OF SOME AVENA SPECIES AND POPULATIONS IN IRAN

Eleven populations of five Avena species were analysed for meiotic characters including chiasma frequency and distribution as well as chromosomal association and segregation. Plants of a single population of A. eriantha showed the presence of 2n = 14 (diploid) and 2n = 4x = 28 chromosome number. Populations of A. barbata and A. wiestii possessed n = 14, while populations of A. sterilis ssp. ludoviciana possessed 2n = 6x = 42 (hexaploid) chromosome number. Tetraploid and hexaploid species showed diplontic behavior and formed only bivalents. The species and populations studied differed significantly in the frequency of chiasmata. B-chromosomes occurred in some of the species studied. Cytomixis and chromosome elimination led to aneuploid and unreduced pollen mother cell formation in the species studied.