Changing the Concentration of the Culture Solution before Harvesting Affected the Component Quality of Takana (Brassica juncea var. integrifolia)

抄録

Hydroponic Takana (Brassica juncea var. integrifolia) was cultivated with a culture solution adjusted to electrical conductivity (EC) of 0.7 or 1.4 dS m^-1, and the culture solution was changed before harvesting. The largest mature leaves of Takana were harvested on day 1, 3, 5, 7 and 10 after changing the culture solution, and the leaf size, fresh weight, nitrate nitrogen content and ascorbic acid content were measured. Using the culture solution adjusted to EC of 0.7 dS m^-1 from the beginning of growth showed significantly lower leaf size and fresh weight, and is inappropriate for agricultural production. In addition, the nitrate nitrogen content was rapidly reduced by changing the culture solution to non-fertilizer before harvesting. The increase of ascorbic acid in hydroponic Takana required more than 7 days after nutrient interruption. In conclusion, the yield may decrease on day 10 after changing the culture solution to no fertilizer. Ascorbic acid was negatively correlated with nitrate nitrogen. Moreover, ascorbic acid increased rapidly when nitrate nitrogen was less than 10 mg/100g FW.