Effect of Partial Replacement of Nitrate by Amino Acid and Urea on Nitrate Content of Non-heading Ch

<正> In this paper, the authors studied the effect of different mixtures of glycine (Gly), isoleucine (Iso), proline (Pro), and urea solutions used as a partial (20%) replacment of nitrate in the nitrate content and quality of non-heading Chinese cabbage and lettuce in hydroponice. Five treatments were done 12 d before harvest. Compared to the control group, Gly had the best effect in reducing the nitrate content of both vegetable leaves and petioles; the mixture of Gly, Iso and Pro ranked second and urea the least. Treatments with