Effect of nitrogen level on growth and glucosinolates content of Chinese kale

A hydroponic experiment was conducted to investigate the effect of different N levels on the growth and anti-cancer glucosinolates content of Chinese kale (Brassica alboglabra). Results indicated that as N level increased from the lowest level of N 100 mg/L to the conventional level of N 200 mg/L, fresh weights of shoot, root and bolting stem increased, while the total glucosinolates content of bolting stem decreased significantly. When N level ranged between N 300 to 400 mg/L, the biomass of Chinese kale was not significantly increased compared with the conventional N level, while the total glucosinolates content was sharply increased contrasted to the two lower N levels of 150 and 200 mg/L, respectively. The different effects of N level on the contents of aliphatic and indolyl glucosinolate were found due to their different original amino acids. The highest content of aliphatic glucosinolates was observed at the N level of 100 mg/L, which was 20 percent higher than that under the conventional N level. While the highest content of indolyl glucosinolates was detected at the N level of 400 mg/L, which was 50 percent higher than that under the conventional N level. In conclusion, N level not only significantly affected the biomass of Chinese kale but also sharply influenced the content of glucosinolates. Although the conventional N level could supply Chinese kale enough nutrition to get high biomass product, relatively higher N level was expected to increase the content of anti-cancer glucosinolates.