Reduction of nitrate ion concentration in Qing-geng-cai (Brassica campestris L. var. chinensis) by extension of growing period and removal of outer leaves
2007
Oba, S.(Shizuoka-ken. Agricultural Experiment Station, Iwata (Japan)) | Matsumoto, M. | Osuka, R. | Arakawa, H.
Nitrate ion content of vegetables has been concerned about consumer's health. Because nitrate ion content of leaf vegetables is higher than that in other vegetables, the methods to keep it at the safety level have been the research subject of worldwide interest. Consequently, we clarified nitrate ion concentrations at various leaf portions and sites of Qing-geng-cai which was one of the special vegetables produced in Shizuoka Prefecture. In addition, we examined the methods to reduce nitrate ion content by extension of growing period and removing outer leaves at harvest. The results obtained are as follows. 1. In Qing-geng-cai, nitrate ion concentration differed from 413 ppm to 6,566 ppm dependent on the leaf positions and sites of individual plant. 2. Nitrate ion content was significantly lower in the outer old leaves, but higher in the inner young leaves. In addition, its concentration was higher in the leaf stalk than the leaf blade as to individual plant.
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