Effect of gamma irradiated Hordeum bulbosum pollen upon haploid frequency in barley following interspecific hybridization

Haploids (monoploids) can be produced in cultivated barley (Hordeum vulgare) by pollination with Hordeum bulbosum and the subsequent elimination of H. bulbosum chromosomes 13]. Pollen of H. bulbosum was gamma-irradiated at doses of 1 to 8 kR to determine if it would lead to a more rapid chromosome elimination and subsequently a higher frequency of haploid barley seedlings. Early embryo development was slower following low dosages of irradiation than at higher dosages and there was no significant improvement in haploid production. At higher dosages, the frequencies of seed set, embryos and haploid seedlings declined. Double fertilization is an apparent pre-requisite of haploid formation and the “intrinsic vigour” of the bulbosum nucleus after fertilization appears to be an important factor in this system of haploid formation.