Objective  Effects of varied nitrogen fertilization on the growth and grain yield of Tartary buckwheat Jinqiao 2 under draught stress were studied.

  Method   Agronomic characteristics, root morphology, and antioxidant enzyme activity of Tartary buckwheat plants under 8 treatments of varied combinations on water and nitrogen supplies were monitored. The treatments included (1) 0D-0N that provided normal water irrigation without added nitrogen fertilization, (2) 0D-LN that used a low nitrogen application with normal water supply, (3) 0D-MN that added a medium level of nitrogen under normal water supply, (4) 0D-HN that applied a high nitrogen fertilization with normal water supply, (5) HD-N0 that imposed a severe drought condition without nitrogen addition, (6) HD-N1 that used a low nitrogen application under severe drought, (7) HD-N2 that fertilized with medium level of nitrogen at severe drought condition, and (8) HD-N3 that supplied high nitrogen under severe drought.

  Result  Agronomically, morphologically, and enzymatically, the treated Tartary buckwheat was significantly affected by the treatments. Supplied with normally required water, the plants were increasingly affected by the increased nitrogen addition to reach a significantly higher peak under 0D-MN than the other treatment before declining (P＜0.05). Under drought, on the other hand, the plant physiochemical indices rose along with increasing nitrogen to maximize by HD-N3 which was significantly higher than other treatments (P＜0.05). With normal water supply, the yield of buckwheat peaked on 0D-MN, which was 2.90 times of that without the fertilization. In contrast, under draught, the yield increased 3.29 folds with a high nitrogen application.

  Conclusion   It appeared that nitrogen fertilization at a rate of 172.413 kg·hm⁻² under draught could not only improve the growth but also increase 1.76-fold on grain weight and 3.29-fold on production yield of Tartary buckwheat.