GENIC HETEROZYGOSITY AND FITNESS IN RYE POPULATIONS WITH CHROMOSOMES-B

Four Korean rye populations with B chromosome frequencies ranging from 15 to 55 per cent were electrophoretically analysed. The values of several components of fitness were also estimated in 1 year at a single density in plants with a different number of heterozygous loci and B chromosomes. All the fitness components decreased as the number of Bs per plant increased. A significant positive correlation between the number of heterozygous loci and both tillering and offspring was found. In addition, a significant negative correlation between the frequency of plants with Bs and the mean heterozygosity was observed. This latter relationship might be due to the high rate of selfing displayed by populations with high frequency of plants carrying Bs, leading to a low genic heterozygosity.