A soybean cultivar, “Seonyu2ho” for double cropping using soy-paste and tofu was developed in 2011 using the pedigree method by crossing “Milyang235ho” and “Jungmo3004ho.” A promising line, YS2441-B-2S-11-3, was selected and named as “Milyang334.” It demonstrated prominent early maturing, shattering resistance, and high yield in regional yield trials (RYTs) from 2017 to 2019, and was released by the name “Seonyu2ho.” The cultivar showed a determinate growth habit, white flowers, grey pubescence, yellow seed coat, yellow hilum, flat-spherical seed shape, and large seed size (27.9 g per 100 seeds). “Seonyu2ho” matured on October 5 (112-growing day cycle) in RYT and was suitable for double cropping with winter crops, such as wheat, barley, and onion. It was resistant to bacterial pustule and soybean mosaic virus and tolerant to lodging in fields. Particularly, “Seonyu2ho” showed a high yield (3.34 ton/ha) and shattering resistance, even if the previously developed early matured cultivars exhibited low yield and easy shattering. Overall, “Seonyu2ho” can contribute to stable soybean production in double cropping.

A soybean cultivar “Chamol” for double cropping for use as soy-paste and tofu was developed using a pedigree method in 2011 as a cross between “Shinpaldal2” and “Keunol.” A promising line, SS99502-2B-89-1-3-4-1-1, was selected and designated as “Milyang210”. It was promising and showed good results from regional yield trials (RYTs) for 3 years from 2009 to 2011 and released with the name “Chamol.” It has a determinate growth habit, white flowers, gray pubescence, yellow seed coat, yellow hilum, spherical seed shape, and large seeds (27.7 g per 100 seeds). The maturity date of “Chamol” was September 18 (100 day growing period) in RYT and it is suitable for double cropping with winter crops such as onion. “Chamol” was resistant to bacterial pustule and soybean mosaic virus and tolerant to lodging in fields. Furthermore, the average yield of “Chamol” was 2.51 ton/ha in the regional yield trials conducted for 3 years from 2009 to 2011.

Cheongja4’ is a black soybean cultivar developed via a cross between ‘Milyang148’ and ‘Daemang’ in 2005. F₁ and F₂ populations were grown for 2 years, and promising lines were selected using the pedigree method from F₃ to F₅. The preliminary yield trial (PYT) and advanced yield trials (AYT) were conducted from 2011 to 2012, and regional yield trial (RYT) in 7 regions was conducted from 2013 to 2015. ‘Cheongja4’ is determinate and has purple flowers, a green cotyledon, and black spherical seeds. Flowering date and maturing date were Aug. 5 and Oct. 19, respectively. With respect to its quantitative characteristics, ‘Cheongja4’ has more pods (50) and smaller seed size (30.1g/100-seed weight) than ‘Cheongja3’ (38 and 35.2g/100-seed weight). ‘Cheongja4’ was revealed to be more tolerant to pod shattering than ‘Cheongja3’ in RYT field and indoor test. ‘Cheongja4’ had high levels of resistance to bacterial pustule and soybean mosaic virus in field and inoculation test. Although its seed quality-related characteristics were similar to those of ‘Cheongja3’, it contained more anthocyanin in the seed coat; this is the main functional component of black soybean. The mean yield of ‘Cheongja4’ in RYT was 314kg/10a, 123% of the yield of ‘Cheongja3’. ‘Cheongja4’ is expected to be widely used for variable functional purposes, such as cooking with rice and the production of processed food.