Cultivated oat (Avenu sativa L.) varieties and lines grown in Northern and Eastern European countries were tested for powdery mildew resistance using eleven Erysiphe graminis f. sp. avenue isolates, which possess the ability to differentiate the five oat powdery mildew resistance (OMR) groups. About 5%) from a total of 207 accessions possessed resistance which was attributable to either documented resistance or to disease response patterns previously not yet detected. Five cultivars and lines showed the resistance of OMR group I, one cultivar possessed the resistance of OMR group 3, one line revealed the resistance of OMR 3 in combination with an additional resistance and 3 cultivars exhibited a resistant response pattern not yet characterized.

The objective of the study was to analyze the genomic structure and allelic composition of the dwarfing Rht-B1, Rht-D1 and Rht8 genes in 37 varieties and breeding samples of soft winter wheat in connection with breeding for lodging resistance in the Republic of Belarus. The molecular cytogenetic marking (C-banding) and DNA typing of genotypes were used. As a result, the analysis of the chromosomal composition of the breeding material showed that 21 winter wheat samples are characterized by the standard karyotype with the genomic structure AABBDD (2n = 42). Five variants of translocations affecting the chromosomes 1B, 3B, 5B, 6B, and 7B were revealed in the karyotypes of the remaining samples. It was found that the chromosomes of the 2nd and 4th homologous groups, in which the main dwarfing genes (Rht-B1, Rht-D1, and Rht8) are localized, did not undergo structural changes. Genotyping showed that 45.9 % of the samples contain one of the dwarfing alleles (Rht-B1b, Rht-D1b, Rht8c) in their genotype. A combination of two commercially significant alleles (Rht-B1b and Rht8c) in the genotype were identified in one of the winter wheat samples. The genotype with a combination of the Rht-B1a, Rht-D1a and Rht8b alleles occurred with the highest frequency (37.8 %) in the analysed breeding material. The Rht-B1b, Rht-D1a, Rht8b; Rht-B1a, Rht-D1a, Rht8a genotypes showed the frequency of 16.2 %. The Rht-B1a, Rht-D1a, Rht8c; Rht-B1a, Rht-D1b, Rht8b; Rht-B1a, Rht-D1b, Rht8j genotypes were identified in 5.4 % of the samples; the Rht-B1a, Rht-D1b, Rht8а genotypes – in 8.1 % of the samples. The analysis of the plant height, taking into account the karyotyping and genotyping data showed that the targeted selection of the most efficient allelic combinations of dwarfing genes is important for the cultivation region. The studies carried out allow us to suggest that the selection by the overwintering level can contribute to the fixation of the Rht8b allele in the breeding material, which is apparently associated with better winter hardiness in the conditions of Belarus.

Reserves of heterosis breeding with efficiency undoubtedly higher, have not been fully applied regarding winter rye crop in Belarus, therefore the creation of heterosis F1 hybrids of winter rye is currently a priority research area in the Republic of Belarus. The paper dwells on the main results of rye breeding for heterosis, discusses the problems of growing hybrid rye varieties in agricultural production. Thus, the first experimental line-population F1 hybrids of winter diploid rye were developed at RUE “Scientific and Practical Centre of Belorussian NAS for Arable Farming”: Lobel-103, Galinka, Plisa and interline hybrid Belgi which in the competitive variety test exceeded the standard by 8.0–14.4 dt/ha. F1 winter rye hybrids form more high stem density by the time of harvesting, which provides higher yields compared with the standard. As a result of breeding experiments on the genetic basis of the Belarusian highly adaptive populations, CMS systems with high combining ability have been created. It was shown that R-type CMS is characterized by high frequency of sterility fixation genes, and therefore there are no problems with maintaining MS-forms in generations. More labor-intensive process is allocation of fertility restorers with a high restore index and with a high combination capacity at the same time. Problems in the cultivation of hybrid varieties of rye associated with a number of genetic and soil-climatic causes were revealed.