Combined Application of Controlled-Release Urea and Common Urea Improves Yield and Nitrogen Use Efficiency in Low-Gluten Wheat

Optimizing nitrogen (N) management is essential for improving grain yield, quality, and nitrogen use efficiency (NUE) in low-gluten wheat, yet the optimal fertilizer strategy remains unclear. A two-year field experiment was conducted to evaluate the effects of common urea (CU), controlled-release urea (CRU), and their combination on yield, quality, NUE, and soil N content in low-gluten wheat. The results showed that, compared with 100% common urea (CU100), 100% controlled-release urea (CRU100) increased grain yield by 8.51% in 2023 and 14.3% in 2024, while 80% controlled-release urea and 20% common urea (CRU80CU20) increased grain yield by 19.2% in 2023 and 23.3% in 2024. These increases were accompanied by enhanced grain number per spike and dry matter accumulation. CRU-based treatments improved NUE, with the highest NUE observed in the CRU80CU20 treatment. Compared with CU100, CRU80CU20 significantly decreased grain protein content while maintaining high grain yield. Path analysis indicated that CRU was positively associated with dry matter accumulation, which in turn was positively associated with grain yield, whereas N translocation was closely associated with grain protein-related quality. In conclusion, CRU80CU20 provided a favorable combination of high grain yield, high NUE, and lower grain protein content, indicating that it is a promising N management strategy for the production of low-gluten wheat.