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.

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.