Partial Factor Productivity as a Tool to Enhance Wheat Seed Quality and Yield Through Nitrogen Fertilization Management

Even though wheat’s response to nitrogen (N) is well studied, practical optimization remains challenging because yield and seed quality often react inconsistently across seasons. For winter wheat, the simultaneous quantification of efficiency indicators that capture N losses and diminishing returns is important. This study evaluated nitrogen (N) fertilization in two growing seasons. This study aimed to adjust N fertilization strategy through different combinations of granular N timing and foliar applications to improve winter wheat yield and technological seed quality while maintaining high fertilization efficiency. Field experiments were conducted over two growing seasons (2021/2022 and 2022/2023) using seven fertilization treatments (Control, TSE_1, TSE_2, TSEH_1, TSEH_2, TSEH_3, and TSH, which correspond to growth stage T—tillering stage; SE—stem elongation phase; H—heading stage) in the range of 140.5 to 194.5 kg ha−1 N. Seed yield and seed quality traits (moisture, hectoliter weight, starch, protein, gluten, and sedimentation value) were measured, and treatment effects were evaluated with ANOVA, correlation, and regression analyses. In 2021/2022, no significant treatment effects were detected for yield or seed quality parameters, indicating that environmental variability dominated crop response. In contrast, in 2022/2023, seed yield, hectoliter weight, gluten content, and starch yield showed significant treatment effects (p ≤ 0.05–0.01), with fertilized variants generally outperforming the Control. Across both seasons, seed quality traits displayed strong internal structure: protein, gluten, and sedimentation were strongly positively correlated, while starch was strongly negatively correlated with these traits and the yield correlated positively with hectoliter weight but negatively with protein and gluten, highlighting a yield–quality trade-off. Importantly, partial factor productivity (PFP) and nitrogen use efficiency (NUE) showed the strongest treatment sensitivity, demonstrating their value for identifying efficient N strategies even when yield and quality responses were season-dependent. Regression analyses confirmed that seasonal conditions modulated nitrogen responsiveness, with NUE and starch yield showing much stronger relationships with nitrogen input in 2021/2022 and 2022/2023, respectively.