Climate change caused by global warming, is predicted to have severe consequences for ecosystems and economic sectors. In the agricultural industry, it is predicted that there will be decreased crop yields resulting from shifting planting seasons, as well as higher temperature and water stress which significantly reduce crop productivity. Kimchi cabbage, a cold-loving plant, is particularly vulnerable to high-temperature stress which can lead to stunted growth, increased susceptibility to pests like soft rot, reduced yield, and lower quality that will negatively impact the Kimchi cabbage market. Kimchi cabbage can be cultivated in highland regions with low summer temperatures and reduced pest occurrence, but rising temperatures and water stress are expected to increase pest pressure, resulting in a rapid decrease in the potential cultivation area of Kimchi cabbage. Currently, research is being conducted around the world to identify physiological mechanisms of heat tolerance at the molecular level, selection of heat-tolerant material, and studies on cellular responses of plants under high-temperature conditions. Despite numerous studies on physiological and biochemical responses of Brassica crops to high temperatures, there is a need to develop heat-tolerant Kimchi cabbage cultivars that can adapt to rapidly changing climates, new strategies for pest control under high-temperature conditions, and mitigation measures to ensure stable cultivation and production.

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 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.