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.

The article presents the results of ecological trials of ten new maize hybrids developed by the ARC “Donskoy” at six points with different moisture supply. According to grain yields there have been identified such valuable for definite conditions hybrids as: ‘Ze 235’ with 5.0 t/ha and ‘Ze 428’ with 6.55 t/ha (ARC “Donskoy”, Zernograd); ‘Ze 182’ with 9.02 t/ha (ARRI of maize, Pyatigorsk); ‘Ze 286’ with 4.92 t/ha (RCG named after P.P. Lukiyanenko, Krasnodar); ‘Ze 428’ with 7.61 t/ha (RPE “Semenovodstvo Kubani”, v. of Ladozhskaya, Krasnodar Area); ‘Ze 331’ with 10.1 t/ha (Agrofirm “Otbor”, v. of Komsomolsky); ‘Ze 428’ with 6.55 t/ha (RusRC “Rossorgo”, Saratov). For the arid conditions there has been recommended the hybrid ‘Ze 428’ with 5.11 t/ha of grain on average at the points with insufficient moisture supply. For the conditions of sufficien moisture supply there has been recommended the hybrid ‘Ze 331’ with 8.06 t/ha at the points with high moisture supply. The new hybrids ‘Ze 182’, ‘Ze 236’, ‘Ze 285’, ‘Ze 286’, ‘Ze 331’, ‘Ze 332’, ‘Ze 333’, ‘Ze 427’, ‘Ze 428’ have been characterized with high responsiveness on the change of growing conditions, regression coefficient (bi) was 1.42–2.02; the hybrid ‘Ze 235’ is found to be an ecologically adaptable genotype (bi = 1). All hybrids belong to ecologically stable genotypes (σd2=0,13–0,74). The hybrids ‘Ze 235’ and ‘Ze 331’ showed the highest index of drought tolerance (72.7 and 67.3% respectively). The early ripening hybrid ‘Ze 182’ (FAO 180), the middle-ripening hybrid ‘Ze 286’ (FAO 250), the middle ripening hybrid ‘Ze 331’ (FAO 300) and the middle-late hybrid ‘Ze 428’ (FAO 400) are the most promising hybrids for practical use according to such their economic-valuable traits as grain productivity, harvesting moisture of grain, resistance to lodging, resistance to smut viruses and ear attachment height.

The improvement of the breeding programs, selection of the optimal group of ripeness depends on the soil and climatic conditions for which varieties and hybrids are developed. One of the most important indicators of climatic conditions is the hydrothermal coefficient (HTC). The purpose of the current study was to analyze the effect of HTC on the productivity of maize hybrids of various groups of ripeness. The studies were carried out in 2014–2019 at the Agricultural Research Center “Donskoy” located in the southern zone of the Rostov Region, characterized by unstable moisture. The objects of the study were 96 interlinear maize hybrids of three groups of ripeness, namely an early ripening group (FAO 150), a middle-early ripening group (FAO 200) and a middle ripening group (FAO 300). There was a systematic use of variants in the trials. The weather conditions of the years 2014 and 2018 could be estimated as arid (HTC = 0.32–0.57). The years 2015, 2016, 2017 and 2019 were of medium aridity (HTC = 0.58–0.89). The HTC determined only for the entire vegetation period did not allow estimating objectively the growing conditions. There has been required a more detailed analysis of the HTC for the periods (months) of vegetation. On average, over the years of study, the middle ripening maize hybrids were characterized with the largest grain productivity (3.98 t/ha). The early ripening maize hybrids were characterized with the smallest productivity (3.31 t/ha). The middle-early ripening hybrids were characterized with the average value (3.80 t/ha). However, in different years, the maximum grain yields were produced by the hybrids of various groups of ripeness, including by the early ripening varieties, that depended on the amount of HTC in different vegetation periods. There have been identified average positive correlation coefficients between the HTC values and maize hybrids’ productivity (r = 0.64–0.74). The use of maize hybrids of various groups of ripeness can stabilize the gross harvest of maize.

The selection of pairs for hybridization requires knowledge about the correlation of the most important quantitative traits that affect grain yield of maize hybrids. The current study was carried out in the Agricultural Research Center “Donskoy” located in the south of the Rostov region with unstable moisture. The years of study (2018–2020) were arid (HThC 0.32–0.89). The purpose of the current study was to evaluate the correlation between quantitative traits and their influence on grain yield of maize hybrids under arid conditions. The objects of research were 96 interline maize hybrids. The analysis has identified the correlation between grain yield and such quantitative traits as ‘one maize ear weight’ (r = 0.64...0.87), ‘number of grains per one maize ear row’ (r = 0.37...0.75), ‘number of grains per maize ear’ (r = 0.32...0.51), ‘number of maize ears per plant’ (r = 0.41...0.53), ‘grain yield’ (r = 0.45...0.64). The traits ‘1000-grain weight’ and ‘number of grain rows’ had either no or slight effect on the formation of grain yield of maize hybrids (r = -0.12...0.28). There have been established the traits, the high values of which were well-combining in one genotype. The values of the trait ‘one maize ear weight’ raised due to an increase of the trait ‘number of grains per one maize ear row’ (r = 0.27...0.74), ‘number of grains per maize ear’ (r = 0.26...0.55), ‘grain yield’ (r = 0.21...0.52). The trait ‘number of grains per maize ear’ raised with an increase in the values of such constituent components as ‘number of grains per one maize ear row’ (r = 0.70...0.76), ‘number of grain rows per maize ear’ (r = 0.59...0.66), and also with an increase of ‘number of maize ears per plant’ (r = 0.32...0.51) and ‘grain yield’ (r = 0.36...0.38). There have been identified difficulty-combining quantitative traits, when the value of the trait ‘1000-grain weight’ decreased with the increase of the ‘number of grain rows per maize ear’ (r = – 0.18...-0.56), ‘number of grains per a maize ear row’ (r = -0.15...-0.31) and ‘grain yield’ (r = -0.01...-0.36).

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