Effects of nitrogen supply forms on the quality and yield of strong and medium gluten wheat cultivars

  Objectives  To provide a scientific basis for selecting suitable nitrogen fertilizer types and efficient nitrogen fertilizer management, we studied the effects of different N forms on plant growth, grain yield, and protein content of strong and medium gluten wheat cultivars.

  Methods  The strong and medium gluten wheat cultivars used in this study were Gaoyou 2018 and Jimai 22. The field experiment was conducted in Xingtai City, Hebei Province. Five treatments were set up under the same N application rate, including no N fertilizer input (CK), amide N fertilizer (Urea), ammonium N fertilizer (NH₄⁺-N), nitrate N fertilizer (NO₃^–-N), and equal NO₃^–-NH₄⁺ (NO₃^–+NH₄⁺). The flag leaf net photosynthetic rate, plant dry matter, N accumulation, grain protein content and yield of the wheat cultivars were measured.

  Results  1) For strong gluten cultivar, the Urea and NO₃^–-N treatments achieved higher grain protein content and yield than other treatments. Compared with other treatments, the dry matter accumulation of wheat at maturing stage (P<0.05) in the Urea and NO₃^–-N treatments increased by 5.9%–17.5%, N accumulation increased by 8.8%–21.9%, N utilization rate increased by 8.0–18.0 percentage points, and N fertilizer agronomic efficiency increased by 9.5%–21.2%. There was no significant difference (P > 0.05) between urea and NO₃^–-N treatments. 2) For medium gluten cultivar, Urea treatment achieved the highest protein content and yield. Compared to other treatments, Urea treatment increased the plant dry matter accumulation at the maturity stage by 4.9%–16.0%, N accumulation by 9.6%–31.0%, N utilization rate by 8.4–22.5 percentage points, and N fertilizer agronomic efficiency by 5.9%–22.4%. 3) Wheat cultivars and N forms (P < 0.05) affected the formation of grain protein components. 4) NH₄⁺-N treatment recorded the lowest dry matter, N accumulation, N efficiency, yield, and protein component in both cultivars.

  Conclusions  Strong gluten wheat cultivar has a high grain protein component. Both urea and NO₃^–-N fertilizers could meet the N requirement of a strong gluten wheat cultivar. Whereas the medium gluten cultivar has a high grain yield and protein content, urea-N shows a better effect than other N forms.