Karytypic investigation of tetraploid populations of Lolium sp.

Since a high level of polyploidy may play an important role in increasing forage dry matter yield, a number of natural populations of Lolium species were investigated for their ploidy level and other kariotype characteristics. In each population of Lolium perenne and L. rigidwn, chromosome characteristics were studied and measured at metaphase stage in five cells. The short and long arms of the chromosomes were measured and analysed. Three polyploid populations were detected within the studied populations. Two populations of L. perenne and one population of L. ligidum were tetraploid with 28 chromosomes. Means of short and long arms of chromosomes, their relative standard errors and the populations karyotypic formula were determined. The three populations were in the same situations based on TF%. Regarding DRL values, since smaler value of this parameter indicates more chromosome asymmetry, one of the L. prenne populations was more symmetric than the other two populations. Based on this parameter L. ligidum population had the most asymmetric karyotype.