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The aim of this research was to evaluate the general and specific combinational ability of inbred winter rye lines in plant height and to identify relatively short-stemmed combinations. The starting material for the crossing was 22 homozygous rye lines carrying sterile cytoplasm of the Pampa type. The male fertile homozygous lines mf H‑1423, mf H‑1247, mf H‑732, and mf H‑842 were used as testers, in which the plant height was 122, 120, 102, and 100 cm, respectively. Test crosses were carried out in isolated plots according to the topcross scheme. A total of 88 simple F1 hybrids were produced. These were tested on plots of 8.0 m 2 in three repetitions. The average height of plants in F1 hybrids was 129 cm and ranged from 114 to 145 cm. The hybrids with the mf H‑732 and mf H‑842 testers turned out to be the shortest-stemmed, and the tallest ones were those with the mf H‑1423 tester. Both general (GCA) and specific (SCA) combinational abilities made a significant contribution to the variance of the plant height trait. The genotypes ms H‑422 and ms H‑1179 had a significantly higher GCA compared to other lines, while ms H‑700 and ms H‑1058 had a lower GCA. Among the testers, the high-stemmed mf H‑1423 and mf H‑1247 lines had a significantly high GCA, and the short-stemmed mf H‑732 and mf H‑842 testers had a significantly low GCA. Combinations involving short-stemmed testers made up a group of the shortest-stemmed hybrids, in which plant height varied from 114 to 120 cm. It has been shown that lines with low effects are of great value for practical breeding not only for GCA, but also for SCA. The ms H‑700 line is of interest, which simultaneously combines low GCA and SCA.

The aim of the study is to quantify the contribution of additive, dominant, and epistatic dispersions to the overall genetic variation of the 1000-grain weight trait to increase the efficiency of breeding heterotic hybrids of winter rye. The experiments were carried out at the experimental base of the Federal Research Center Nemchinovka (Moscow oblast). The starting material was ten male sterile homozygous inbred lines carrying the Pump-type cytoplasm. These lines were crossed with two male fertile test lines: mf H-842 and mf H-1247. Test crosses were carried out in 2019 on two isolated plots according to the topcross scheme. The resulting hybrids and their parent forms were tested in 2020 and 2021 on plots of 8 m 2 in twofold repetition. The test for epistasis and decomposition of the genetic varianсе into additive and dominant components was carried out by the method of Jinks, Perkins, and Brees (1969). The data show that the additive interaction of genes, as well as incomplete dominance, plays the main role in determining the trait of granularity. A stable ratio of these interactions was established over the years: the proportion of additive effects varied at the level of 83.9–84.7%, and the proportion of dominant effects at the level of 15.3–16.1%. The indicator of the degree of dominance   was less than one and varied slightly over the years. It follows from this that dominant alleles affecting gross grain do not completely suppress the effect of their recessive alleles. For this reason, simple interlinear hybrids inherit an intermediate phenotype compared to the parent forms. The most coarse-grained hybrids were obtained by crossing lines ms H-1054, ms H-649, and ms H-1090 with the coarse-grained tester mf H-1247. It is concluded that, in the synthesis of commercial rye hybrids, it is necessary to strive to ensure that all parent forms are gross-grained. To obtain such lines, it is advisable to use methods of recurrent selection as well as convergent and cumulative breeding.

Identification of the inbred lines perspective for combining abilities of winter rye is an important stage in the hybrid breeding cycle. The objective of the surveys is to evaluate the general and specific combining abilities of the inbred lines of winter rye with a topcross method. Thirty rye homozygous lines carrying the sterility-inducing cytoplasm of the Pampa type served as the maternal inheritance patterns. Four male fertile homozygous lines mfН-1432, mfН-1423, mfН-1147, and mfН-1842 were used as testers. Test crossings were performed on the spatially isolated fields in 2019. Overall, 120 simple interlinear F1 hybrids were produced. Their testing was carried out on the plots of 8.0-m 2 area with two field replicates. The Valdai cultivar was used as a standard at the population level. The F1 hybrid crop yields varied from 5.08 to 7.55 t/ha at the parameter average value of 6.27 t/ha within the experiment. The hybrids containing lines msН-1185-1 were considered highest-yielding crops. Their crop yields varied from 6.92 to 7.48 t/ha relative to the tester. Frequency of occurrence of hybrids F1 with reliably high competitive heterosis comprised 20 of 120, or 16.7%. Both the general (GCA) and specific (SCA) combining abilities made the essential contribution to dispersion of the crop-related traits. In addition, the portions of the GCA and SCA effects comprised 91.2 and 6.9% of dispersion of the crop-related traits, respectively. A high variance GCA/SCA ratio indicates rather substantial genetic divergence between the inbred lines used in breeding. Rather high GCA is recorded for seven sterile lines, such as msH-1185-1, msH-1185-2, msН-1179, msН-1238, msН-700, msН-48, and msН-1247. The line mfН-1147 was considered best on GCA among the tester lines. Lines msН-451, msН-577, msН-842, msH-1185-2, and msН-1190 and testers mfН-1432 and mfН-1423 showed great SCA effects. The average crop yield of the hybrids containing lines of high GCA was reliably higher than that in the hybrids containing lines of high SCA (6.76 vs. 6.24 t/ha, true T-value T fact = 3.38 > T 05 = 2.22). However, nine sterile lines possessed significantly lower GCA. A positive correlation between the line GCA effects and the levels of their crop yields was revealed ( r = 0.59, true T-value T fact = 2.30 > T 05 = 2.22).