Aneuploidy in induced autotetraploid populations of Festuca pratensis, Lolium multiflorum and Lolium perenne

Abstract

The aneuploid frequencies were determined in two autotetraploid populations of Festuca pratensis, St 839 and Sv 01243. Vegetative and generative properties of euploids, hypoploids, and hyperploids were studied. Before chromosome counts, the seed lots were sieved into five seed size fractions. Chromosome numbers were determined by a modification of conventional root tip squash. Chromosome number varied with seed size. This variation was caused by differences in hypoploid frequencies between the fractions. In St 839 the lightest seeds contained 30% hypoploids and the heaviest ones 2%. In Sv 01243 the hypoploid frequencies varied from 20% to 1%. The total aneuploid frequency in St 839 was 29.3% with a slight predominance of hyperploids. In Sv 01243 the aneuploid frequency was 26.0%, with about equal size of the aneuploid chromosome classes. Vegetative and generative characters were measured. Euploids were superior to aneuploids, and hyperploids to hypoploids in both populations. The effects of aneuploidy were more pronounced on the generative characters. The euploids were heading earlier than the aneuploids. The differences were generally highly significant.