The purpose of the study is the application of the method of multi-criteria estimation to select the initial material of various direction of maize breeding. The studies were performed in the year of 2017–2018 in two different regions of trials, in the arid area of the ARC “Donskoy” (Zernograd) and in the moisture area of the All-Russian Research Institute of Maize (Pyatigorsk). 10 parental forms of maize hybrids ‘Alpha M’, ‘Almaz M’, ‘Avrora S’, ‘Milena M’, ‘Istok S’, ‘Mirt M’, ‘Malvina S’, Raduga S’, Maya M’, ‘Prestizh M’ used as testers in breeding programs were taken as initial material. The studied forms were characterized by a diversity in the value of their main economically valuable traits. Significant variability was identified in infertility of plants (V = 56.0%), smut infection (V = 46.4%) and fragility of a stem below a cob (V = 43.4%). Average variability was identified in grain productivity (V = 14.8–18.2%), drought resistance index (V = 10.5%), harvesting moisture of grain (V = 18.6%). The use of the complex of main economically valuable traits for the integrated assessment (SD), taking into account the specified contributions (Rk) and weight coefficients (Wi), made it possible to rank the initial material according to its value for various areas of selection. There have been identified the testers ‘Mirt M’, Maya M, ‘Istok S’ with the best integral values (SD = 2.63–5.65) for breeding on drought tolerance. ‘Istok S’, ‘Milena M’, ‘Avrora S’ (SD = 2.14–4.07) have been recommended as the testers in breeding programs to breed the varieties with low harvesting moisture of grain. There has been identified a universal tester ‘Istok S’ which is suitable for various directions of maize breeding. Thus, the multi-criteria estimation can be used in the breeding process to select initial material that meets the requirements of the planned breeding directions.

Abstract. The development of cytosterile maize hybrids in Russia is a necessary condition for their wide implementation into production. To develop such hybrids, it’s greatly relevant to be aware how the lines react to sterile cytoplasm. The study was carried out at the Agricultural Research Center “Donskoy” (“ARC “Donskoy”) in 2010–2021. The purpose of the current study was to classify the new self-pollinated maize lines according to the composition of the fertility-restoring genes of the Paraguay (C) type of CMS, to optimize the number of analyzing test-crosses. Methods. As initial material there have been used 45 new self-pollinated maize lines and 8 sources of sterility with different genetic structure. The method of complete top-crosses there have been identified 360 maize hybrids, used for estimation of the new lines’ reaction. Results. According to the study results, the sterility-fixing lines KV 204, SP 286, DS 255, SP 207, DS 180, which had no fertility-restoring genes in the dominant state, belonged to the I class. As the natural complete constant fertility-restorers there has been recommended to use the lines of the VIII class KV 498, KV 272, KV 7/07, SP 357, RD 261, DS 295, SP 210, SP 197, DS 177, DS 188, having all three dominant genes Rf4, Rf5, Rf6 in the genotype. The incomplete sterility-fixing lines included the lines of the II–IV classes (KV 3, RD 245, SP 198, etc.). The incomplete fertility-restoring lines were the lines of the V–VII classes (KV 469, RD 331, KV 276, etc.). There has been found out that the most common lines were the lines of the V (24.4%) and VIII (22.3 %) classes. The scientific novelty of the study was an optimal number and genetic structure of the analyzers WF 9c of the V class, Lc of the VI class and W 401c of the VII class, which are necessary for crossings and allow identifying lines according to the fertility-restoring genes.

Seeds of maize hybrids in the Russian Federation are obtained using CMS, therefore it is necessary to transfer the developed hybrids to a sterile basis to introduce them into production. The purpose of the work is to study the reaction of self-pollinated maize lines to various types of CMS. There was estimated the response of 26 self-pollinated maize lines to the “M” type of CMS and the response of 23 lines to the “C” type of CMS. The simple sterile hybrids “Milena M”, “Madonna M”, “Krucha M”, “Istok C”, “Nimfa C”, “Malvina C”, which are the mother forms of the new three-linear maize hybrids have been used as the testers of the sources of sterility. The self-pollinated lines have been classified according to the response to the “M” type of CMS as sterility fixers (11), incomplete sterility fixers (7), fertility reducing agents (6), non-uniform in reconstructing ability (2). In relation to the “C” type of CMS there were identified 10 sterility fixers, 3 incomplete sterility fixers, 7 fertility reducing agents, 3 non-uniform in reconstructing ability. The reducing agents of Moldavian type of CMS “FC 18 A”, “T 22 A”, “DS 768/83-3”, “DS 768/85-4”, “DS 768/85”, “DS 768/85-5” are of the greatest practical interest as they can be used as natural reducing agents (paternal forms) in the developed hybrid combinations. The constant natural reducing agents of the “C” type of CMS (“T 22 A”, “PLS 61”, “DK 22/325”, as paternal forms of hybrids grown on sterile cytoplasm of the “C” type) are of practical value. The use of sterile testers in hybridization allows simultaneously with the development of new hybrids to start the first stage of their transfer to a sterile basis, namely to evaluate the response of the lines to the sterile cytoplasm.

The current paper has presented the results of breeding work on maize in the Agricultural Research Center “Donskoy”. The three-line and double interlinear middle early and middle ripening maize hybrids of various economic use ‘Zernogradsky 242 MV’, ‘Zernogradsky 282 MV’, ‘Zernogradsky 288 MV’, ‘Zernogradsky 299 MV’, ‘Zernogradsky 354 MV’, ‘Zernogradsky MV’, ‘Stepnyak MV’ were developed and included into the State List of Breeding Achievements from 2006 to 2020. The Competitive Variety Testing has identified a new high-heterosis simple hybrid ‘Zernogradsky 352 MB’ and the new early ripening hybrids ‘Krucha M × KB 215’, ‘Krucha M × SP 56/57’ with low harvesting grain moisture. The main method used to develop maize hybrids was an interline hybridization using heterosis in the first generation (F1 ). There have been determined the priority directions of further breeding, namely early ripeness, grain humidity-transfer intensity during ripening, drought resistance, high starch content in grain. There has been developed new initial material for each direction of breeding. There have been selected the introduced testers (‘Alpha M’, ‘Almaz M’, ‘Aurora S’, ‘Milena M’, ‘Istok S’) to develop early-ripening hybrids. There have been identified the early and middle-early ripening self-pollinated lines ‘C 207’, ‘RD 12’, ‘TVA 308’, ‘PLS 61’, ‘KB 215’, etc., with a high grain humidity-transfer intensity during ripening (0.95–1.30% per day), low harvest moisture content of grain (10.8–13.8%). There have been developed the new self-pollinated waxy maize lines (24/29/5, 25/64/10, 26/8, 26/4, 26/80, 24/28) with 68.1–69.8% of amylopectin starch in grain. There have been identified the new self-pollinated maize lines resistant to water stress (DS 498/217-3, DS 257/85-5, DS 498/203, KB 262, etc.) promising for breeding drought-resistant maize hybrids.

Changing climatic conditions and the loss of immunity to diseases and pests of the developed varieties make breeding work to create new genotypes of great necessity. The new middle-early maize hybrid ‘Zernogradsky 299 MB’ of universal direction of economic use (for grain and green fodder) has been developed in the “Agricultural Research Center “Donskoy”. The hybrid is three-linear; it belongs to the varieties with crown yellow grain Zea mays L. indentata. It possesses high values of the main economically valuable traits. The average grain productivity through 3 years of competitive variety testing (2014–2016) was 5.36 t/ha, the variety yield exceeded the standard variety ‘Zernogradsky 291 AMB’ on 0.41 t/ha (8.3%). The average productivity of green mass is 27.6 t / ha, which is higher than that of the standard variety on 2.4 t/ha (9.5%). The new hybrid is resistant to lodging (2.1% of lodged plants), drought-resistant, resistant to smut on a natural background (0.4% of affected plants), has a high starch percentage (71.9%). In 2018, according to the results of the State Variety Testing, a new hybrid was introduced into the State List and approved for use in the Central Blackearth and NizheVolzhsky regions to cultivate it for grain and green fodder. It has a high potential for grain productivity. The maximum yield (11.23 t/ha) was obtained in the Central Blackearth region on the Oboyansk plot of the Kursk region, which is higher than the standard variety ‘Voronezhsky 279 CB’ on 2.03 t/ha (22.1%) with lower grain harvesting moisture (on 1,6%) than the standard variety.