Abstract: The effect of dicyandiamide (DCD) on the accumulation of nitrate in Brassica campestris L. ssp. chinensis var. utilis Tsen. et Lee. was investigated in the present study. The results indicated that DCD, which was applied at 20 d before harvest of the vegetable, had a significant effect on lowering the
amount of NO ₃^-_-N and enhancing the level of NH₄⁺-N in the substrate. Consequently, DCD supp ressed excessive accumulation of nitrate in the vegetable, while yield of the vegetable was not affected by the app lication of
DCD, suggesting that the decrease of nitrate accumulation in vegetable treated with DCD was resulted from the inhibition of nitrification and the reduction of nitrate absorption.

Key words: Brassica campestris, Dicyandiamide, Nitrate, Accumulation, Nitrate nitrogen