Analysis of variance showed the presence of a significant variation in the studied traits depending on the testing sites with the exception of the general combining ability of the grain weight per plant of male parents and the productive tilling capacity of female lines. The values of the variability of the general combinational ability are presented in Table 1.
Analysis of variance revealed significant differences in the GCA and SCA of the traits under study (Fact > Ftabl), which made it possible to proceed to the estimates of the GCA and SCA effects.
The determination of the studied traits involved additive (GCA) and non-additive effects (SCA), and the predominance of certain types of gene interactions depended on the cultivation conditions (Table 2).
Regardless of the growing location, additive effects prevailed in the determination of such traits as plant height, spike length, number of grains per spike, grain weight per spike, productive tilling capacity. And in the demonstration of the trait “thousand-grain weight” in the rice system conditions in the Kyzylorda region, the main influence was exerted by the no allelic effects of genes, in contrast to the piedmont zone conditions of the Almaty region. If, in the conditions of the Kyzylorda region, the allelic effects of genes exceeded the no allelic one sin the length of the growing season, in the piedmont zone of the Almaty region this trait was equally controlled by both additive and non-additive gene interactions.
The proportion of the additive effects of the genes of seed parents also depends on the influence of the environment. In contrast to the piedmont zone of the Almaty region, in the conditions of the rice systems of the Aral Sea region, the mean squares of the GCA of the female lines exceeded the GCA values of the testers, being inferior in terms of the SCA in the plant height and spike length. The number of grains per spike, thousand-grain weight, grain weight per spike, and the length of the growing season in both zones were mainly determined by the additive genes of male parents; however, in the conditions of rice systems, its slight decrease was observed. The cultivation zones had a significant impact on the demonstration of the specific combining ability of the thousand-grain weight and the length of the growing season. In the conditions of saline soils of the Aral Sea region, the thousand-grain weight, in the piedmont zone of the Almaty region, the length of the growing season was noted by more pronounced no allelic interactions.
Plant height. A distinctive feature of the Syrian barley samples is their dwarfness (not higher than 50 cm), as the most possible genetic source of short-stature, which is of certain interest for breeding varieties in the conditions of the irrigated zone of the Almaty region. The best in breeding terms are the varieties WI2291/Roho/WI2269and Rihane, distinguished by persistent low GCA in height and positive in the number of grains, thousand grain weight, grain weight per spike, in combination with low GCA effects in the length of the growing season simultaneously in two zones (sources of early maturity). Variety-testers Saule, Donetskiy 8, have a fairly low GCA in height, but in the course of further analysis of the combining ability, their negative impact on all traits of productivity have been revealed. However, as studies by Dianga et all. (2020) have shown, the results of one population cannot be extrapolated to another population. The effect of the gene must be assessed for each population, that is, the values of the specific combining ability must be assessed and taken into account.
One of the determining factors in the zoning of a particular variety of barley in the conditions of the rice crop rotation of the Kyzylorda region is the height of the plants since it is mainly cultivated as cover crop perennial grasses. Therefore, the development of varieties with optimal stem sizes (not lower than 75 cm), combining early maturity to avoid overgrowth of grasses above, is an urgent direction in barley breeding for this region.
Considering the greatest practical value of these traits, the best seed parents should be recognized as the Odessa 100 and Harmal varieties, in which a very favorable combination of high GCA and SCA has been noted, besides the additive variance in quantitative terms somewhat has predominated over the non-additive one, which indicates the possibility of positive transgressions in subsequent generations.
Spike length. No varieties with stable high estimates of the GCA were identified simultaneously at two sites according to the spike length. We can note Harmal, which is characterized by relatively stable positive estimates, that is, independent of the environmental differences of high and average GCA. In the conditions of the Aral Sea region, the Odessa 100 variety, which also has high variances of the SCA, can be used in heterosis and linear selection to improve this trait (Table 3).
Number of grains per spike. In the conditions of the rice systems of the Aral Sea region, the lines WI2291*2/WI2269 and Harmal, and tester Odessa 100 were identified according to GCA, which were also characterized by high values in the “number of grains per spike” (on average 22–24 pcs.) in comparison with other genotypes being studied. The lines Rihane and Harmal and testers Odessa 100 and Saule are distinguished by high variances of the SCA, which are recommended to be used to obtain certain heterotic combinations.
In specific combinations, the best were the hybrids WI2291*2/WI2269 x Odessa 100; WI2291/Roho/WI2269 x Saule; WI2291*2/WI2269 x Donetskiy 8; Harmal x Saule. In the conditions of the piedmont zone of the Almaty region, positive estimates of the GCA effects were noted for the line WI2291/Roho/WI2269 and Rihane. According to this trait, there is no presence of varieties stable in terms of GCA; only Odessa 100 can be identified, distinguished by positive high and average estimates of the GCA effects, which is also characterized by high values in the “number of grains per spike” (on average 22–24 pcs.) in comparison with other genotypes being studied, that is, the greatest expression of the trait dominates, therefore, it has the largest number of alleles that positively determine the trait. The values of the GCA effects and the SCA variants of productivity indicators are presented in Table 4.
Thousand grain weight. In the conditions of the Kyzylorda region, the lines Rihane and the Odessa 100 variety were identified according to the GCA; WI2291*2/WI2269 – according to the SCA, which can be used to highlight certain successful combinations when crossing by this trait.
The piedmont zone of the Almaty region determined the high combination value of the lines WI2291/Roho/WI2269, in contrast to the Aral Sea zone, which negatively affected the grain size. Regardless of the growing areas, estimates of the GCA effects in the Odessa 100 variety are highly significant, in combination with a high SCA in the Aral Sea zone, which is of great value for both synthetic and heterosis selection. In specific combinations, the best were the hybrids: WI2291*2/WI2269ХDonetskiy 8; WI2291*2/WI2269 хOdessa 100; Harmal X Saule.
Grain weight per spike. The conditions of the saline soils of the Aral Sea region had a negative effect on the GCA of varieties WI2291/Roho/WI2269, Saule, Donetskiy 8, Saule in terms of grain weight per spike, but did not change the estimates of the Odessa 100 variety. Whereas, the conditions of the piedmont zone, on the contrary, had a positive effect on the GCA of the lines WI2291/Roho/WI2269 and Rihane, which also had high GCA effects in thousand grain weight and number of grains per spike, respectively. The hybrids obtained on their basis are characterized by high productivity. Special attention should be paid to the samples Harmal and WI2291/Roho/WI2269, which have been distinguished by a high variance of the SCA in the rest traits of productivity, which can be recommended for obtaining promising combinations for the selection of transgressive lines.
Thus, varieties and lines stable according to the GCA were determined simultaneously in two geographical points:
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- Odessa 100 in two traits: the length of the growing season and thousand grain weight;
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-Donetskiy 8 in two traits:the number of grains per spike and thousand grain weight;
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-Saule in three traits: spike length, the length of the growing season andthousand grain weight;
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- Rihane in two traits: plant height and grain weight perspike;
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- WI2291/Roho/WI2269, WI2291*2/WI2269 and Harmal in three traits: plant height, spikelength and the length of the growing season.
In general, the varieties Rihane, WI2291/Roho/WI2269 and the variety-tester Odessa 100 with high GCA and SCA effects, little dependent on growing conditions, which can serve as donors of important selection parameters, are of the greatest practical interest.
I would like to note the effectiveness of remote hybridization when genotypes of other subspecies of foreign selection are selected as parent forms. In our studies, we observed a huge genetic diversity in plant height, ear length, number of grains per ear, early maturity, resistance to lodging, morphological features (double-row, intermediate, six-row forms, awnless, bush type, hulless), which allows breeders to conduct high-quality selection, expand and replenishes the working collection. Such studies avoid the process of unification of the germplasm of grain crops and increase the success of breeding work. Currently, we are breeding pure lines selected from the obtained hybrid populations and are being studied in the breeding nursery of the 2nd year (Fig. 4).