After identification and screening, Nanjing Agricultural University has 16 high-quality germplasm of common Chinese cabbage, such as dwarf yellow, Suzhou green, dwarf white stem, Nannong dwarf yellow and tetraploid Suzhou green inbred lines.
Shao et al. (2006) showed that the nitrate content of different varieties of Chinese cabbage in the same season and the same variety of Chinese cabbage planted in different seasons was obviously different (Table 5-2).
Comparison of nitrate content of different Chinese cabbage varieties in different cultivation seasons
Note: The "grade" in the table is the grading evaluation standard of nitrate content in edible parts of vegetables put forward by Shen Mingzhu and others according to the ADI value stipulated by the World Health Organization and the Food and Agriculture Organization of the United Nations, namely, 1 grade ≤432mg/kg, grade 2 ≤785mg/kg, grade 3 ≤ 1 440mg/kg and grade 4 ≤ 3 65438.
Wang Liping (2002) comparatively screened the nitrate content of 46 Chinese cabbage varieties in four different seasons: spring, summer, autumn and winter. The results showed that the difference of nitrate content among Chinese cabbage varieties was extremely significant, and the highest and lowest difference could reach 2000 ~ 4000 mg/kg (fresh weight). The winter experiment showed that among Chinese cabbage varieties, Jiangsu Aihuang, Hongqiao Ailv, Black Oil Cabbage and Xiangtan Aibai had higher nitrate content, while Shanghai Green, Reyou No.2, Nannai Cabbage, Hongmingqing Cabbage and Spoon Cabbage had lower nitrate content. The results of spring experiment further confirmed that there were significant differences in nitrate content among Chinese cabbage varieties. The nitrate content of Jiangsu Aihuang, Xiangtan Aibai, Hongqiao Ailv and black oil cabbage is still high, and the order from high to low is Shanghai Green, Ailv Cabbage, Reyou No.2, Aikangqing and Hongmingqing. The results of summer experiments showed that Jiangsu Aihuang, Xiangtan Aibai, Aihei Leaf, Black Cabbage, Japanese Green Cabbage and Hongqiao Aicai were higher in content, especially Jiangsu Aihuang, while Shanghai Christina, Ainai Cabbage, Aikanglv, Reyou No.2 and Shanghai Xia Dongqing were lower in content. The results of autumn experiment also showed that the nitrate content of different varieties of Chinese cabbage was significantly different, among which Xiangtan Aibai, Jiangsu Aihuang, Baisha 1 cabbage and Hongqiao Ailv were higher, while Shanghai Green, Ailv Cabbage, Hongmingqing and Reyou No.2 were lower.
According to the above results, the common Chinese cabbage germplasm resources with low nitrate content are: Shanghai Qing, Reyou No.2, Dwarf Cabbage (with low nitrate content in spring, summer, autumn and winter), Hongming and Qing Dynasties (with low nitrate content in winter, spring and autumn), Aikangqing, Shanghai (with low nitrate content in spring and summer) and Spoon Cabbage (with low nitrate content in winter).