Maize is considered an unsurpassed silage crop, so breeding in this direction is of great relevance. The study was carried out at the FSBSI «Agricultural Research Center «Donskoy» in 2019–2021. The purpose was to study productivity and nutritional value of the new silage hybrid combinations, to identify dependencies to optimize the breeding process. In order to develop new hybrids, there was applied the method of interline hybridization using heterosis in the first generation. The objects of research were 24 hybrids of the early-maturing, middle-early and middle-maturing groups. In each group, there have been identified the new hybrid combinations that are found promising for cultivation for silage and green fodder. In the early-maturing group, a new hybrid ‘Krucha M × KV 215’ formed the largest productivity of green mass (28.2 t/ha) and dry matter (9.41 t/ha). The hybrid had 6.56 t of feed units per 1 ha, 0.48 t of digestible protein and 90.0 GJ/ha of exchange energy. In the middle-early group, a new hybrid ‘Krucha M x KV399 MV’ produced 29.4 t/ha of green mass, 10.35 t/ha of dry matter, 7.49 t of fodder units per 1 ha, 0.57 t of digestible protein, 96.14 GJ/ha of exchange energy. In the middle-maturing group, the best hybrid was a new hybrid ‘KV 399 × 9837V’, which had the highest rates among all the hybrids studied. The hybrid produced 7.88 t of fodder units per 1 ha, 0.64 t of digestible protein and 98.64 GJ/ha of exchange energy. There have been identified the signs that should be used in the development and selection of maize hybrids for silage, such as plant height, cob attachment height, number of leaves per plant, length of a vegetation period.

A waxy maize variety differs from other varieties, as its grain contains only amylopectin starch, which is considered a very valuable product for use in food, technical industry, and medicine. An insufficient amount of initial material hinders the development of Russian waxy maize hybrids. The purpose of the current study was to develop and select self-pollinated lines that could be promising for breeding waxy starchy maize hybrids. The study was carried out in the FSBSI Agricultural Research Center “Donskoy” in 2019–2021. As the initial material there were used 54 new constant self-pollinated waxy maize lines, developed by the standard method. There have been identified such self-pollinated lines as 24/5, 24/18, 24/29(5), 24/78, 25/2(3), 26/8 with 68.1–70.2 % of amylopectin starch. The new lines were characterized by high values of the most important traits, namely seed productivity (0.91–1.75 t/ha), resistance to lodging (0–0.6 % of lodging plants), smut ‘virus’ infection (0–3.6 % of infected plants), low and medium harvesting moisture content of grain (14.7–16.3 %). The identified lines can be recommended for use in crossbreeding programs to develop new waxy maize hybrids. There has been established that amylopectin starch percentage in grain of self-pollinated maize lines negatively correlates with protein percentage (r = –0.55) and oil (r = –0.29), which must be taken into account when selecting for initial material. There has been established a mean positive correlation between starch percentage and seed productivity (r = 0.33) and number of cobs per 1 plant (r = 0.33). The selection of genotypes with high values of these traits has been recommended when developing a starchy initial material of waxy maize.

Domestic interline maize hybrids are predominantly three-way cross hybrids in structure, and foreign breeding and seed companies prefer simple interline hybrids. In order to improve the competitiveness of domestic breeding, it is necessary to reorient to simple hybrids, which, in turn, requires information on whether simple maize hybrids have an advantage in specific soil and climatic areas. The purpose of the current study was to conduct a comparative study of new simple interline and three-way cross maize hybrids according to grain productivity and uniformity of economically valuable traits under unstable moisture supply. The study was carried out on the experimental field of crop rotation of the laboratory for maize breeding and seed production of the FSBSI “ARC Donskoy” in 2019–2021. The objects of the study were 10 simple and 10 three-way cross new domestic maize hybrids developed by the method of complete topcrosses. The establishment of field trials, records, biometric measurements and phenological observations were conducted in accordance with the methodological recommendations for conducting field trials with maize. There has been found that productivity of simple hybrids (3.49–4.65 t/ha) turned out to be significantly larger than that of three-way cross hybrids (2.84–3.70 t/ha), the mean excess was 0.78 t/ha or 23.6 %. Simple hybrids were characterized with the best uniformity in a length of a vegetation period (V = 0.58–2.13 %), height of maize ear attachment (V = 5.0–11.3 %), plant height (V = 2.8–4.8 %), and, consequently, better harvesting adaptability. There has been found a negative mean correlation (r = –0.49...–0.69) between grain productivity and variation of traits in terms of maturation, plant height and height of maize ear attachment. There has been found no correlation between the structure of interline maize hybrids and such traits as grain harvest moisture, resistance to lodging and smut “virus”. Due to a set of traits there has been identified a new simple interline maize hybrid ‘Zernogradsky 367’.

A subspecies of waxy maize (Zea mays L. ceratina) is characterized by the fact that its grain contains 100 % amylopectin starch, a valuable raw material for confectionery production, the manufacture of polymers, and a blood substitute. The absence of domestic waxy maize hybrids in the State List of Breeding Achievements necessitates the study in this area of breeding. The purpose of the current study was to identify dependencies that make it possible to increase the efficiency of the breeding process when developing waxy maize hybrids. The study was carried out at the FSBSI “ARC “Donskoy” in 2020–2022. The objects of the study were 36 waxy maize hybrids developed by the method of interline hybridization. The studied traits differed in the degree of variation. High coefficients of variation were identified in the traits ‘grain productivity’ (V = 30.1 %) and ‘one cob weight’ (V = 21.5 %). The traits ‘number of rows’ (V = 8.4 %) and ‘grain yield during threshing’ (V = 8.2 %) turned out to be slightly varying. An increase in the values of any studied trait resulted in an increase in grain yield. However, the signs of productivity were not equivalent according to their effect on the formation of the grain productivity of the waxy maize hybrids. There have been identified the most influential traits of productivity, such as ‘number of cobs per 1 plant’, ‘one cob weight’ and ‘number of seeds per cob’. The correlation between them and grain productivity is positive, close (r = 0.73±0.12 – 0.82±0.10). The identified traits have been positively associated with the rest (r = 0.30±0.16 – 0.74±0.12), the selection of samples with high values does not reduce the values of other productivity traits. The identified dependencies must be taken into account when selecting the initial material and when developing waxy maize hybrids.