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Rhizomania is considered as one of the most important biotic stresses of sugar beet production in Iran and the world. The use of resistant cultivars is the most efficient, economical, and healthy way to increase crop yield and reduce damage from soil-borne diseases such as rhizomania. Despite the development of monogerm cultivars in the country, there is still a demand in the market for high-yielding multigerm cultivars resistant to rhizomania. To develop this variety, five pollinator inbred lines available in the Gene Bank of SBSI, which had one or two disease resistance characteristics, were used. In September 2017, the seeds of each of the inbred lines were planted in Hamedan along with commercial male-sterile multigerm single-cross seeds with the code I13*SB36 (maternal-base), and in the spring of 2018, crosses were made in isolated plots, and hybrid seeds were produced. In 2019, the produced hybrids together with two domestic multigerm varieties (Jam and Motahar) as resistant controls, as well as one sensitive control (IC) and one imported multigerm resistant control (Aras 101) as nine cultivars trial-based on randomized complete block design in four replications in five regions of Hamedan (Ekbatan station), Fars (Zarghan station), Khorasan Razavi (Targh station), West Azarbaijan (Miandoab station), and Alborz (Motahari Karaj station) in the conditions of Rhizomania were compared. Based on the results of the preliminary evaluation and ensuring the superiority of the hybrids compared with the domestic resistant cultivars, all five hybrids with the codes SBSI-175 to SBSI-179 and the aforementioned domestic, and foreign resistant cultivars were entered into the value for cultivation and use (vcu) test. Hybrids based on a complete random block design with four repetitions in the form of a nine cultivar experiment in the years 2021 and 2022 in six regions including Hamadan (Ekbatan station), Fars (Zarghan station), Razavi Khorasan (Targh station), Khorasan Razavi (Jovin station), West Azarbaijan (Miandoab station), and Alborz (Motahari station) with different levels of Rhizomania disease were compared. In a total of two years, compared with other hybrids, the hybrid SBSI-177 had the highest white sugar yield in Karaj (12.47 ton.ha-1), Mashhad (13.9 ton.ha-1), Miandoab (9.06 ton.ha-1), and Hamedan (6.79 ton.ha-1), and, in general, Aras 101 and the hybrid SBSI-177 produced the highest white sugar yield with an average of 9.30 and 8.80 ton.ha-1, respectively, and a significant difference between them was not observed. In 2023 and based on the results of the vcu test, the hybrid SBSI-177 along with the Motahar variety were evaluated in the demonstration farms of three regions of Fars (Zarqan station), Khorasan Razavi (Toroq station), and Alborz (Motahari station) with different levels of infection. The results obtained showed the superiority of root yield, sugar yield, and white sugar yield of the hybrid SBSI-177. Therefore, the SBSI-177 hybrid with high white sugar yield and good performance stability has the potential to be introduced as a new multigerm cultivar, and this new hybrid is the first diploid multigerm hybrid cultivar with resistance to rhizomania and suitable for spring cultivation in different regions of the country.
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