Inheritance of resistance to Ustilago nuda [Jens.] Rostr. in some spring barley cultivars

The inheritance of resistance to loose smut (Ustilago nuda) in seven cultivars of spring barley has been examined. The performed studies showed that, resistance to two different groups of U. nuda races in respect of their virulence is determined by a single allele pair in the cvs. Anoidium and Inerme 2-r and by two allele pairs in the cvs. CI 13 662, Dorsett, Jet and OAC 21. In the cv. Abyssinian, resistance to a group of races 2 is determined by a single allele pair, whereas that to a group of races 4 - by two allele pairs. In all studied cultivars (except Anoidium) the resistance dominates over sensitivity. Resistance to the both studied groups of U. nuda races is determined by similar genes in the cvs. Dorsett and CI 13 662, as well as in Dorsett and OAC21, and additionally to a group of races 4 in the cvs. Abyssinian and OAC 21. No similarity was found between resistance genes in the case of two allele pairs in the cvs. Jet, Abyssinian and CI 13 662 (group of races 4) as well as in Jet, Dorsett and OAC 21 (in both groups of races), and in the case of a single allele pair in the cvs. Inerme-2-rowed and Abyssinian (group races 2).