‘Ganghan’ is a high-yielding soybean (Glycine max L. Merrill) cultivar developed for improved shattering resistance and suitability for mechanized harvesting. It was bred through pedigree selection after an artificial cross between ‘Taeseon’ (female parent) and ‘Cheonga’ (male parent) in 2015. ‘Ganghan’ is a determinate type with an average main stem length of 65 cm and first pod height of 19.6 cm, which is favorable for mechanical harvesting. Compared to the control cultivar ‘Daewonkong,’ it showed stronger lodging tolerance and carried a genetic allele associated with pod shattering resistance. In disease resistance evaluations, it exhibited higher resistance than ‘Daewonkong’ to soybean mosaic virus (G6H), bacterial pustule, and black root rot. Regarding seed quality, it contained 38.8% protein, 17.6% oil, 86.1% unsaturated fatty acids, and 3,124 μg/g total isoflavones. The tofu yield was 232%, with mechanical properties and color comparable to ‘Daewonkong.’ In fermentation processing tests, ‘Ganghan’ recorded a γ-PGA content of 11.4 mg/g and amino nitrogen content of 390 mg%, indicating potential use in traditional fermented soy foods. In regional yield trials (RYT) conducted across 10 locations from 2020 to 2022, ‘Ganghan’ had an average yield of 3.58 tons/ha, 14% higher than that of ‘Daewonkong’. The adoption and expansion of ‘Ganghan’ is expected to contribute to increased domestic soybean productivity, harvest efficiency, and cultivation stability under changing climate conditions, thereby improving the domestic soybean self-sufficiency rate (Registration No. 10459).

Bacterial pustule is a major bacterial disease in most soybean-growing regions of Korea, resulting in soybean yield reductions of up to 60%. In this study, we aimed to understand the differences in disease severity caused by three strains of Xanthomonas citri pv. glycines, including two newly differentiated strains (K29 and K100) and the conventional representative strain, 8ra. Seventeen major soybean cultivars and 14 breeding lines were inoculated and compared for their reactions to the three strains of Xcg. The two new strains caused higher levels of disease severity, resulting in a greater number of susceptible cultivars. The landrace PI 547711, like Williams 82, was highly resistant to all Xcg strains; however, the other six cultivars that were resistant to 8ra, including Daepung2, were susceptible to the new strains (K29 and K100). In particular, the most widely grown cultivars, Daewon and Daepung2, were highly susceptible to K100. All of the breeding lines except two were also vulnerable to the new strains, K100 and K29. Of the breeding lines, SS05004-1-1-4-2-3-4 and SS05022-5-4-2-4-4-4 were resistant to the three Xcg strains, at similar levels to that of Williams 82. The breeding lines and cultivars evaluated in this study may be used to develop breeding materials resistant to new Xcg strains in the future. In addition, establishment of an improved disease evaluation system for bacterial pustule, by using multiple representative strains, is strongly recommended for breeding programs, to increase the efficiency and accuracy of selection for resistance as the pathogenic diversity of X. citri pv. glycines changes.