Optimized nitrogen timing enhances wheat grain composition and processing quality under saline–alkaline conditions

Wheat ( Triticum aestivum L.) is one of the most important cereal crops globally, and its productivity and processing quality are often constrained by saline–alkaline soils, which impair nitrogen (N) uptake and grain quality development. Optimizing nitrogen management is therefore essential for improving wheat yield and quality in such marginal environments. However, limited studies have comprehensively evaluated how different nitrogen management strategies influence both grain composition and end-use performance under saline–alkaline conditions. A two-year field experiment (2023–2025) was conducted in Yancheng, Jiangsu, China, to assess six nitrogen management strategies under an equal nitrogen rate (270 kg hm -2 ), including conventional split urea, blended fertilizer, and controlled-release fertilizer with different application timings. Nitrogen management significantly affected grain yield, compositional traits, rheological properties, and end-use quality. Across both growing seasons, the split application of controlled-release fertilizer (N5) consistently achieved the highest grain yield, with increases of 11.4%–11.7% compared with conventional split urea (N1). N5 also enhanced protein content, gluten strength, and glutenin accumulation, while promoting amylopectin enrichment and improved starch pasting characteristics. These compositional changes were associated with improved dough stability and resistance, reduced noodle break rate, and increased mantou specific volume. In conclusion, optimized split application of controlled-release fertilizer improves both yield and processing quality under saline–alkaline conditions, suggesting that nitrogen timing plays a key role in wheat quality development. These findings highlight the importance of nitrogen timing rather than nitrogen rate in stress-prone agroecosystems. • Split controlled-release nitrogen (N5) improved wheat yield by over 11% under saline–alkaline soils. • N5 enhanced protein accumulation, gluten quality, and dough rheology compared with split urea. • Nitrogen form and timing shifted starch composition, increasing amylopectin and pasting stability. • Enhanced glutenin polymerization and amylopectin synergy improved noodle and mantou texture. • Split controlled-release fertilization synchronizes N supply with demand, optimizing yield–quality balance.