Horticultural Science and Technology ISSN:1226-8763(Print) 2465-8588(Online) 원예과학기술지

The study was conducted to investigate the effects of nitrogen fertilization on the occurrence of black speck and storability of kimchi cabbage ‘Cheongock’ and ‘Ryouckgwang’ s. Kimchi cabbage was cultivated with three different levels of nitrogen fertilization: half, normal, or double (24, 48, or 96 kg/10 a). Quality parameters measured were reducing sugar (glucose and fructose) content, color (Hunter L, a, and b), occurrence of black speck, and gene expression of polygalacturonase (PG ). At harvest, ‘Ryeokgwang’ showed similar maturity at all nitrogen fertilization levels, whereas double nitrogen fertilization induced fast-paced growth in ‘Cheongock’ compared to the normal fertilization. Expression of PG was not significant difference in ‘Ryeokgwang’, PG was expressed more extensively in the ‘Cheongok’ compared to ‘Ryeokgwang’ and expression increased between 3 and 6 weeks of storage. The hunter L value in the ‘Ryeokgwang’ was maintained until 6 weeks, which was the recommended optimal storage period, however it gradually decreased up to 9 weeks. By contrast, normal level of fertilization with nitrogen maintained quality until 9 weeks in ‘Cheongock’. The reducing sugar contents of ‘Cheongock’ were higher than those of ‘Ryeokgwang’, with glucose more abundant than fructose. Double fertilization led to lower soluble sugar contents in both s. Occurrence of black speck was related to the amount of nitrogen fertilization. Black speck was more severe with double excess and lack of nitrogen fertilization in ‘Ryeokgwang’ and ‘Cheongock’ s, respectively. In conclusion, normal nitrogen fertilization maintained the quality of kimchi cabbage until 6 and 9 weeks in ‘Ryeokgwang’ and ‘Cheongock’, respectively.