Abstract: The nitrate content of 52 samples of yellow Chinese chive and 109 samples of Chinese chive collected from the north bank of Dianchi Lake were determined, one field trial was also conducted to investigate effects of nitrogen fertilization, nitrification inhibitor (DCD and elemental sulfur), and light illumination on content of nitrate in yellow Chinese chive. The present results indicated content of nitrate ranged from 379.2 mg·kg^-1 to 1 354.6 mg·kg^-1 with an average of 774.1 mg·kg^-1 in yellow Chinese chive; and from 258.2 mg·kg^-1 to 3 878.0 mg·kg^-1 with an average of 1 615.7 mg·kg^-1 in Chinese chive. Content of nitrate in different yellow Chinese chive tissue decreased in the following order: Kelly leaf > vagina > lamina. Content of nitrate in yellow Chinese chive decreased after exposing light illumination at 6:00 am, until 12:00 am; subsequently increased gradually and reached at a peak value at 2:00 pm, thereafter decreased again. Field trial results demonstrated that reducing 20% of nitrogen fertilizer decreased by 13.6% nitrate content of yellow Chinese chive without losing yields; DCD decreased nitrate content of yellow Chinese chive by 12.9%, and increased yields 11.1%; element sulfur increased significantly yields 13.5%, and reduced its nitrate content by 8.6%; exposing sunlight of yellow Chinese chive before harvesting also resulted in decrease of its nitrate content. The measures mentioned above could decrease obviously nitrate content of yellow Chinese chive, which are prone to be extensively applied in the study area.

Key words: yellow Chinese chive, nitrate, nitrification inhibitor, illumination