FERTILITY OF 17 COLCHICINE-INDUCED PERENNIAL TRITICEAE AMPHIPLOIDS THROUGH 4 GENERATIONS

Seed set and pollen stainability were determined for 17 perennial colchicine-induced amphiploids (2n = 42 or 56) derived from sterile triploid and tetraploid F1 hybrids of Agropyron, Elymus, Hordeum and Sitanion spp. Chromosome doubling restored fertility; the level of fertility in the originally doubled hybrids (C0 generation) declined in advanced generations. Fertility stabilized in most hexaploids after the C1 generation: fertility of most octoploids continued to decline. Seed set (seeds/spike) of 9 hexaploid amphiploids averaged 17.5, 18.9 and 17.4 in the C1, C2 and C3 generations, respectively. Eight octoploid amphiploids averaged 8.1, 9.1 and 4.2 seeds/spike, respectively, over the same 3 generations. Synthesis of fertile Triticeae grass species appears to be feasible at the hexaploid level but not at the octoploid level.