Kimchi cabbage (Chinese cabbage) is a very common Korean traditional vegetable, cultivated across 32,000 ha, which accounts for about 13% of the total vegetable cultivation area in Korea. Since 2010, frequent occurrences of extreme weather conditions caused a shortage of summer, winter, and autumn Kimchi cabbage. Therefore, the National Institute of Horticultural and Herbal Science (NIHHS) selected a haploid breeding method of microspore culture to develop inbred lines that show resistance under extremely low or high temperature for Kimchi cabbage production. ‘Wonkyo20051ho’ is a double-haploid (DH) inbred line developed using the microspore culture method. Eleven heat resistant parental plants were selected through summer cultivation of 37 resources collected in 2014. Microspore culture was efficient in regenerating four resources, from which 13 DH inbred lines were developed. After artificially inoculating ‘Seosan’ clubroot with low concentration inoculum, 7 inbred lines showing moderate resistance were selected. As a result of the autumn cultivation of 83 breeding plants, including 6 selected inbred lines, the ‘18-FH98’ inbred line forming tight heads with yellow inner leaf under low temperature was finally selected during the 2018 autumn field trial. The selected DH inbred line was named ‘Wonkyo20051ho’ and is expected to be a valuable breeding material possessing tolerance to low temperature and clubroot.

A cultivar of lettuce (Lactuca sativa L.) with sharply large oval and purple leaf, ‘Jahokmaschima’, which has late bolting and a high yield, was developed from a cross between ‘Bulkkoch’ (dark red leaf color and early bolting) and ‘Cheongpung’ (high yield). The cross and selection for advanced lines was conducted by the pedigree method between 2005 and 2011. The advanced lines were evaluated for yield and adaptability at six locations in Korea (Gangwon-do, Gyeonggi-do, Chungcheongbuk-do, Jeollabuk-do, Gyeongnam-do, and Jeju-do) for 3 years until 2014. The ‘Jahokmaschima’ lettuce has a gray seed color, and the leaf type of the matured stage is a large oval leaf, leaf no. 67 per plant, and late bolting. In particular, the ‘Jahokmaschima’ has good resistant to tip burn in the growth period. The anthocyanin and vitamin C content of ‘Jahokmaschima’ were lower than those of ‘Tomallin’, at 4.05 mg/100g and 27.7 mg/100g, respectively. The BSL (bitter sesquiterpene lactones; latucin, 8-deoxylactucin, and lactucopicrin) content of ‘Jahokmaschima’ was lower than that of ‘Tomallin’, at 2.120 µg/g DW. Compared with ‘Tomallin’, the marketable yield of ‘Jahokmaschima’ was 1% higher (at 374 g per plant) and particularly improved late in bolting in high temperature cultivation in the field. The shelf-life of ‘Jahokmaschima’ was similar to ‘Tomallin’ at 4ºC. Furthermore, it tasted better, and was crispier and sweeter than ‘Tomallin’. Thus, we recommend that the new cultivar ‘Jahokmaschima’ is suitable for cultivation in spring and fall.

The radish (Raphanus sativus L.) is one of the major vegetables of Korea and is consumed as the main ingredient of kimchi. To improve the texture of radish kimchi, herbs, and soup, we attempted to develop a cultivar with a hard texture. Using species native to Jeju Island, we bred ‘Wonkyo10045ho’ which produces short, elliptically shaped roots with a hard texture. Generation progress was made via the self-fertilization method using bud pollination. We selected individuals with good horticultural characteristics from each of five generations grown from 2006 to 2010. Finally, in 2015, the line was named ‘Wonkyo10045ho’, and the granting of plant variety rights (Grant number 6527) was certified in 2017 following an application for the protection of new plant varieties (application number 2015-398). The root characteristics of ‘Wonkyo10045ho,’ include an oval shape, mixed white and green root skin, and a white inner root color. ‘Wonkyo10045ho’ had a sugar content of 4.9 Brix, with excellent sweetness, good taste, and strong pithiness. The average number of seeds per plant obtained via pollination by bees in a small net house was 609.1, suggesting that the strength of its self-incompatibility was not strong and male sterility might be advantageous. Therefore, it is expected that this variety will be useful as a material for improving the competitiveness of domestic farmers and for stable radish exports.

A new red butterhead lettuce (Lactuca sativa L.) with transverse broad elliptic, red leaves, ‘Sun Red Butter’, with late bolting and high yield, was developed from a cross between ‘Jajusangchu’ (red leaf color and half crisp) and ‘Dukseomjeokchukmyeon’ (high yield). The crossing and selection for advanced lines was previously carried out using the pedigree method during the period 2001–2009. The advanced lines were evaluated for yield and adaptability at several locations in Korea (Gangwon-do, Gyeonggi-do, Chungcheongbuk-do, Jeollabuk-do, Gyeongsangnam-do, and Jeju-do) in 2011. The type of matured stage is early and medium butterhead lettuce. The shelf life of ‘Sun Red Butter’ was four weeks longer than that of ‘Germania’ at 4°C. The anthocyanin content of ‘Sun Red Butter’ was lower than that of ‘Germania’ at 11.2 mg/100 g. The BSL (latucin+8-deoxylactucin+lactucopicrin) content of ‘Sun Red Butter’ was higher than that of ‘Germania’ at 32.8 µg/g, DW. The marketable yield of ‘Sun Red Butter’ was higher than that of ‘Germania’ by 67% (at 621.4 g per plant), and ‘Sun Red Butter’ showed a particularly improved yield under high-temperature cultivation in the field. Furthermore, ‘Sun Red Butter’ had better taste characteristics and was crisper and sweeter than ‘Germania’. Therefore, we recommend that the new cultivar ‘Sun Red Butter’ would be suitable for cultivation in spring and fall. Furthermore, this new cultivar could be harvested in a single harvest, as in a head lettuce, and could therefore be managed more efficiently and economically by farmers.

Kimchi cabbage (known as Chinese cabbage) is major vegetable in Korea. An inbred line of ‘Wonkyo20038ho’, was developed by the National Institute of Horticultural & Herbal Science, RDA in Republic of Korea. The microspore culture was carried out using ‘Chunhuigohangwang’ which was introduced from China in 2002. Among 3 DH inbred lines, ‘Wonkyo20038ho’ inbred line was finally selected after field exhibition in 2009. The horticultural traits of ‘Wonkyo20038ho’ inbred line; half-open head, white inner leaf colour, and dark green outer leaf colour. The average (for four years) head weight was 2025.3g, and head width and height were 15.8cm and 32.4cm, respectively. Head shape was narrow elliptic and degree of overlapping leaf was medium. Numbers of outer and internal leaves were 14.1 and 49.8, respectively. Harvest maturity was mid-late maturing type and average of seed yield for five years was 926 seeds. In addition, ‘Wonkyo20038ho’ inbred line is suitable for salad in that it possessed few trichome and narrow elliptic head shape.

Kimchi cabbage (known as Chinese cabbage) is one of the major vegetable in Korea. An inbred line ‘Wonkyo20042ho’, was developed by the National Institute of Horticultural & Herbal Science, RDA in South Korea. The first cross carried out using ‘Norang gwandong’ which had been introduced to Korea in 2007. During segrerating generations, bud pollination carried out using selected plants to fix genetic materials. ‘Wonkyo20042ho’ inbred line was finally selected by breeders from commercial companies at the field exhibition at 2011. The horticultural traits of ‘Wonkyo20042ho’ inbred line were as follows; half-open head, yellow inner leaf colour, and dark green outer leaf colour. The average head weight was 1899.2g, head width and height were 17.5cm and 27.9cm, respectively. Numbers of outer and internal leaves were 14.3 and 66.5, respectively. Harvest maturity was mid-late maturing type and average of seed yield for three years was 723 seeds. In addition, ‘Wonkyo20042ho’ inbred line showed resistance to clubroot disease (race 4 single spore isolation) and possessed thin leaves and small sized head.