‘Godangok1’, a sweet corn hybrid obtained by crossing the inbred KSE13 (female) and KSE37 (male), was developed by the maize breeding team at the National Institute of Crop Science (NICS), Rural Development Administration, Korea, in 2016. ‘Godangok1’ has the sugary enhancer (se) gene, and the ear is yellow-white. The number of days to silking of ‘Godangok1’ was 59, similar to ‘Danok3’ (check variety), but ear length and the ratio of kernel set length to ear length (18.7 cm and 96%, respectively) were superior to those of ‘Danok3’. The resistance to Bipolaris maydis, Exserohilum turcicum, and Ostrinia furnacalis was similar to that exhibited by ‘Danok3’, whereas the lodging tolerance was stronger than that of ‘Danok3’. The fresh ear yield of ‘Godangok1’ was 6,530 ears, with 1,139 kg per 10a, and the sugar content was 20.8 °Brix. The hundred kernel weight was 27.4 g, smaller than that of ‘Danok3’. The flavor was excellent and assigned a sensory score of 5.7. Unique properties of ‘Godangok1’ coded by the recessive se gene are eliminated due to crosspollination when growing along with other types of corn such as general corn (sh, sh2, bt, etc.). Therefore, it must be isolated in time or space and harvested in order to produce high-quality sweet corn (Registration No. 7506).

‘Daanok’, a new maize F₁ hybrid (Zea mays L.), is developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2013. The high-yielding hybrid, named ‘Daanok’ was bred by crossing between two inbred lines, ‘KS174’ and ‘KS175’. It is a yellow semi-flint maize hybrid (Zea mays L.). After preliminary yield trial and advanced yield trial of Daanok in Suwon for two years, regional yield trial of that was subsequently carried out for evaluation of its growth and yield at three different locations from 2011 to 2013. The silking date of Daanok is earlier than that of the check hybrid, ‘Jangdaok’. The plant height of Daanok is 229cm, similar to Jangdaok, and its ear height ratio is similar with that of Jangdaok.It has resistance to lodging. There are much of the No. of ear per 100 plants. The ear length of Daanok is similar with that of Jangdaok. The weight of 100 seeds of Daanok is the same with that of Jangdaok. It has strong resistance to northern leaf blight (Exserohilum turcicum) and southern leaf blight (Bipolaris maydis). It has strong resistance to ear lot. It has moderate resistance to corn borer. The grain yield (7.34 ton/ha) of Daanok was 23% higher than that of Jangdaok. The seed production of Daanok has gone well due to a good synchronization of flowering period during crossing between the seed parent, KS174, and the pollen parent, KS175, in Yeongwol and F1 seed yield was 2.38 ton/ha. Daanok would be a suitable cultivar to all plain area in Korea.

Cheongdaok, a new single maize (Zea mays L.) variety, was developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2010. This high-yielding hybrid was produced by crossing two inbred lines, KS159 and KS155. KS159 is the seed parent and KS155 is the pollen parent of Cheongdaok. It is a yellow dent maize hybrid. After the preliminary yield trial and advanced yield trial of Cheongdaok in Suwon for two years, the regional yield trial was subsequently carried out for evaluation of its growth characteristics and yield at four different locations from 2008 to 2010. The silking date of Cheongdaok is one day earlier than that of the check hybrid, Kwangpyeongok. Compared to Kwangpyeongok, the Cheongdaok show short in plant height and low in ear height ratio. It has resistance to lodging. The stay-green degree and the ear ratio of Cheongdaok are similar to Kwangpyeongok. It has moderate resistance to southern leaf blight (Bipolaris maydis) and strong resistance to northern leaf blight (Exserohilum turcicum). It has moderate resistance to black streaked dwarf virus (BSDV), ear lot, and corn borer. The dry matter yield 20.24 ton/ha and the total digestible nutrient (TDN) yield (13.80 ton/ha) of Cheongdaok were similar to Kwangpyeongok. The grain yield (8.51 ton/ha) of Cheongdaok was higher than that of Jangdaok. The seed production of Cheongdaok was well processed due to a good synchronization of flowering period during crossing between the seed parent KS159 and the pollen parent KS155, and the F1 seed yield was 1.8 ton/ha in Yeongwol.