Variability of new self-pollinated maize lines’ response to CMS depending on the sterility source and weather conditions of the year

The wide introduction of new maize hybrids into production is possible only if they are transferred to a sterile basis. This requires data on the lines’ response to cytoplasmic male sterility (CMS). The purpose of the current study was to classify new self-pollinated maize lines according to their ability to fix and restore based on various sources of sterility and contrasting weather conditions during the conducted estimation. The study was carried out at the FSBSI Agricultural Research Center “Donskoy” in 2022–2024. The conditions during the study were contrasting (HTC = 0.49 – 2022, HTC = 0.83 – 2023, HTC = 0.22 – 2024). As the sterility sources there were used the forms М 1 and М 2 with different sterilizing capacity of the Moldavian (‘M’) type, and the forms С 1 , С 2 with different sterilizing capacity of the Bolivian (‘C’) type of CMS. The objects of the study were 15 new constant (I 6 ) self-pollinated maize lines and 60 test-cross hybrids obtained from analyzed crossings. The response of the self-pollinated lines depended on the source of sterility and the weather conditions of the year of study. The fertility level of testers with the participation of the sources M 2 and C 2 was higher than that of testers of the sources C 1 and M 1 . In the arid year of 2024, the selfpollinated lines SK 7, SK 9 and SK 11 reduced the fertility level according to the ‘C’ type from partial fertility (class 2) to complete sterility (class 0), or from complete fertility (class 5) to partial fertility (class 3). According to the ‘M’ type, there was a fertility decrease in the lines SK 11 and SK 12. There have been identified such new self-pollinated maize lines as SK 1, SK 6, SK 7, SK 8, SK 14 and SK 15, which are sterility fixers of the ‘M’ type of CMS. These lines are valuable as maternal forms when transferring maize hybrids developed with their participation to a sterile basis. There have been identified the lines SK 5 and SK 9 as the natural fertility restorers of the ‘M’ type, which are valuable for use as paternal forms of hybrids. According to the ‘C’ type of CMS, the sterility fixers SK 5, SK 12, SK 14 and the constant fertility restorers SK 2, SK 3, SK 6, SK 10 and SK 13 are of the greatest interest.