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.

‘Saebong’ is a double cropping potato variety bred by the Highland Agriculture Research Institute, NICS, RDA, in 2010. Although the major double-cropped potato cultivar of Korea, cv. Dejima, with a dormancy period of 50-60 days after harvest was introduced in 1978, it is susceptible to physiological disorders, such as abnormal tubers and cracking, and common scab. The ‘Chubaek’ variety matures very early and has a dormancy period similar to that of cv. Dejima, yet it is highly susceptible to potato virus Y and has a low dry matter content. ‘Saebong’ was obtained by crossing ‘Daegwan2-8’ with ‘DH9-231’ in 2002. Seedling and line selections were performed from 2003-2004, and yield trials were carried out from 2005-2006 in Gangneung and Pyeongchang. Regional yield trials were conducted in spring and autumn in Namhae, Jeju, and Gangneung from 2007-2008 and in Muan, Jeju, and Gangneung in 2009. This variety produces many white flowers and berries, narrow green leaflets and petioles, and round tubers with beige-colored skin and white-colored flesh. Its dormancy period, when stored at 20℃, was 50-60 days after harvest in spring, similar to cv. Dejima and Chubaek. The average tuber yields in spring and autumn regional trials were 40.4 and 30.5 ton⋅ha^-1, respectively. It is susceptible to common scab but highly resistant to potato leafroll virus and potato virus Y. Its dry matter content was 21.56% and 20.60% in spring and autumn, respectively (similar to those of cv. Atlantic and cv. Goun). It produces brighter colored potatoes and can be used to process potato chips and table stock after autumn cultivation in the potato double cropping area of Korea (Registration No. 4873).

‘Jowoo’, an early maturing, high biomass yielding rice (Oryza sativa L.) cultivar with high feed value and multiple disease-insect resistance, was developed for winter forage crop-whole crop silage (WCS) rice double cropping. It was derived from a cross between a high biomass and multiple disease resistant line ‘Suweon519’ and an early flowering, high yielding Tong-il type variety ‘Gaya’ that harbored Bph3 and BPH26, conferring brown planthopper (Bph) broad resistance. This cultivar had a growth period of approximately 106 days from seeding to heading, 97 cm culm length, 24 cm panicle length, 12 panicles per hill, 120 spikelets per panicle, and 1,000-grain weight of 22.1 g as brown rice in the central plain region of Suwon. This early flowering rice variety was tolerant to premature germination and cold stresses, especially showed higher grain fertility than ‘Nokyang’ at a cold-water (17℃) irrigated screening nursery. Further, ‘Jowoo’ exhibited high lodging resistance in the yellowing ripening stage, an optimal period for harvest. In addition, ‘Jowoo’ was resistant to leaf and neck blast, bacterial blight (race K1, K2, K3, K3a), rice stripe virus, and small Bph and was also moderately resistant to Bph. Its average dry matter yield for three years reached 18.2 MT/ha, the highest among early flowering rice varieties and 19% higher than that of ‘Nokyang’. This cultivar had 72.2% total digestible nutrients, which is also higher than that of ‘Nokyang’. In the Korean peninsula, ‘Jowoo’ grows well in the central and southern plains and can be harvested 30 days after heading. This helps improve its feeding value and digestion rate in livestock (Grant No. 8133).

A new double cropping potato variety, ‘Gangseon’, was bred by the Highland Agriculture Research Institute, National Institute of Crop Science (NICS), RDA, Korea, in 2016. ‘Gangseon’ was obtained from the cross between ‘Daegwan1-83’ and ‘Chubaek’ in 2006. Seedling and line selection was performed from 2008 to 2009, and preliminary and advanced yield trials were carried out with ‘Gangseon’ from 2010 to 2013 in Gangneung city. The regional yield trials were conducted in Gangneung, Muan, and Jeju from 2014 to 2016. ‘Gangseon’ has light purple flowers, green narrow leaflets and petioles with medium anthocyanin coloration, round tubers with yellow russet skin, and yellow flesh. The dormancy of ‘Gangseon’ stored in 20 ℃ was 60-70 days after harvesting, which is longer than those of ‘Dejima’ and ‘Chubaek’, but shorter than that of ‘Superior’. The average yields of tubers in the spring and fall seasons were 36.6 and 21.2 ton⋅ha^-1, respectively, in the regional yield trials. It is susceptible to common scab and potato virus Y, but has high resistance to potato leaf roll virus, potato virus X, early blight, and late blight. The dry matter contents were 22.1% in spring and 19.8% in autumn. The adaptation area of ‘Gangseon’ is the southern coastal area, including Jeju Island, Korea. The plant variety protection right of ‘Gangseon’ was registered in April 2020, and its grant number is 8081.

A new double cropping potato variety, ‘Geumseon,’ was bred by Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration in 2014. ‘Geumseon’ was obtained from the cross between ‘Chuyoung’ and ‘Daegwan1-87’ in 2005. The seedling and line selections of ‘Geumseon’ were performed from 2006 to 2007 and preliminary and advanced yield trials were carried out from 2008 to 2011 in Gangneung. The regional yield trials were conducted in three locations (Gangneung, Muan, and Jeju) from 2012 to 2014. ‘Geumseon’ has white flowers, green narrow leaflets and petioles, and short oval tubers with beige skin and white flesh. The dormancy of ‘Geumseon’ was 60-70 days in 20℃ after harvest, which is longer than those of ‘Dejima’ and ‘Chubaek’. The average yield of tubers in spring and fall were 42.1 and 25.8 ton ha^-1 in the regional yield trials, respectively. It is susceptible to common scab, late blight, and potato virus Y, but has a high resistance to potato leaf roll virus and potato virus X. The dry matter content was 21.9 and 23.0% in spring and fall season, respectively. Plant variety protection right of ‘Geumseon’ was registered in November 2018, and its grant number is 6924.

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.

A soybean cultivar for soy-paste, ‘Hwangkeumol’, was developed from the cross between SS92414 (crossing line of ‘Pokwangkong’ and ‘Suwon163’) and ‘Hwaeomputkong’ by soybean breeding team in the National Institute of Crop Science (NICS) in 2010. A promising line, SS99409-2B-11-5-4, was selected and designated as the name of ‘Milyang202’. It was prominent and had good result from regional adaptation yield trials for three years from 2008 to 2010 and released as the name of ‘Hwangkeumol’. It has a determinate growth habit, white flower, gray pubescence, yellow seed coat, yellow hilum, spherical seed shape and large seed (28.6 grams per 100 seeds). Maturity date of ‘Hwangkeumol’ was as early as September 15th. Therefore it is suitable for double cropping system. ‘Hwangkeumol’ was resistant to bacterial pustule and resistant to soybean mosaic virus, the major soybean diseases in Korea and tolerant to lodging in fields. The average yield of ‘Hwangkeumol’ was 2.51 ton per hectare in the regional yield trials carried out for three years from 2008 to 2010.

Registration number: 4901

A soybean cultivar ‘Yonpoong’ which has safety high yield for double cropping system introduced winter forage crop was released by agricultural resource research institute of ARES, Gyeunggi Province in 2010. The goals of breeding were for large seed size, high yield, and resistance to disease such as spotting disease. ‘Yonpoong’ was derived from the cross of ‘Suwon 191’, which large seed size and high yield, and ‘Suwon 126’, which early maturity cultivar, and short stem. The preliminary, advanced and regional yield trials for evaluation and selection were carried out from 2005 to 2010. ‘Yonpoong’ has a determinate growth habit with purple flower, grey pubescence, brown pod color, yellow seed coat, yellow cotyledon, elongated seed shape, large seed size(28.7 g per 100 seeds). The maturing date was sept. 22. Tofu yield was similar to that of check cultivar ‘Daewonkong’. The average yield of ‘Yonpoong’ was 3.34 MT/ha in the regional yield trials(RTY) carried out in Korea from 2008 to 2010 which 38 percent higher than the check cultivar ‘Daewonkong’.

A new soybean cultivar ‘Manpoong’ for tofu soybean was released by ARES, Gyeunggi Province in 2009. The goals of breeding were for large seed size, high yield, and resistance to disease such as bacterial pustule. ‘Manpoong’ was derived from the cross between ‘Dongsan 121’, which has large seed size, yellow seed coat, and characteristics of superior tofu, and ‘Sprite 87’, which has early maturity. The preliminary, advanced and regional yield trials for evaluation and selection were carried out in 2003 and from 2005 to 2009, respectively. ‘Manpoong’ has a determinate growth habit with white flower, grey pubescence, dark brown pod color, yellow seed coat, yellow cotyledon, elongated seed shape, and large seed size(29.5 g per 100 seeds). The maturing date was Sept. 29. The content of crude protein, crude oil, unsat. fatty acids, isoflavone, total amino acid which affected the production rate of tofu was higher than those of the check cultivar ‘Taekwangkong’. The production rate of tofu was 15 percent higher than the check cultivar ‘Taekwangkong’. The average yield of ‘Manpoong’ was 2.87 MT/ha in the regional yield trials(RYT) carried out in two location at double cropping system in Korea from 2007 to 2009, which was 12 percent higher than the check cultivar ‘Taekwangkong’.