The North China Plain is one of the major wheat cultivation regions. As a cornerstone of global food security, wheat makes the enhancement of its yield critically important. Sulfur critically regulates photosynthesis, antioxidant defense, and grain filling dynamics. To elucidate the physiological mechanisms of S in wheat grain filling and guide field practices, a two-year field experiment (2022–2023 and 2023–2024) was conducted in the North China Plain using two dominant cultivars, Jimai 20 (JM20) and Yannong 999 (YN999). Four sulfur (ammonium sulfate) gradients (S1: 15 kg ha⁻¹; S2: 30 kg ha⁻¹; S3: 45 kg ha⁻¹; S4: 60 kg ha⁻¹) and a control (S0) were applied at the jointing stage via a drip fertigation system. The key findings reveal that optimal S application (YN999: 45 kg ha⁻¹; JM20: 30–45 kg ha⁻¹) enhanced post-anthesis photosynthetic capacity by increasing flag leaf SPAD values and superoxide dismutase (SOD) activity while reducing malondialdehyde (MDA) accumulation, thereby delaying leaf senescence. These improvements translated into optimized grain filling parameters: YN999 and JM20 exhibited 2.27–5.62% and 13.20–13.86% increases in mean grain filling rate, 3.92–4.73% and 2.11–4.36% extensions in grain filling duration, and 7.62–7.83% and 9.55–10.23% boosts in thousand grain weight, respectively. Consequently, yield increased by 0.58–1.54 t ha⁻¹ for YN999 and 1.36–1.49 t ha⁻¹ for JM20. Under drip fertigation conditions in the North China Plain, sulfur application at 30–45 kg ha⁻¹ effectively enhances wheat yield. These findings provide fertilization guidance for the development of precision agriculture and can help alleviate the local soil sulfur deficiency trend.

A two-year field experiment was conducted to clarify the regulatory effects of nitrogen (N), phosphorus (P), and potassium (K) combined with drip fertigation on the yield, yield components, and grain quality of winter wheat in lime concretion black soil (Calcaric Cambisols). The objective was to screen a sustainable fertilization model for coordinating high yield and quality in the Huang-Huai-Hai Plain. An L₁₆(4³) orthogonal design was adopted to investigate yield, protein content, wet gluten, test weight (TW), and grain hardness. Range analysis and ANOVA were used to evaluate factor effects and interactions. The results showed that N was the dominant factor affecting yield and quality (Rank 1), followed by K (Rank 2), while P showed the weakest effect. Compared to the control (N0P0K0), the optimized N–P–K combination increased grain yield by an average of 315.0% and enhanced grain crude protein by 55.3% over the two seasons. The optimal combination for maximum yield was N170P30K120 (kg/ha), which optimized the source–sink relationship by balancing spike density and 1000-grain weight. High N (220 kg/ha) combined with low P and high K achieved the best nutritional quality. The 3D response surface analysis confirmed significant synergistic interactions between N–K and N–P in promoting grain filling and protein synthesis. Rational NPK drip fertigation, particularly when synchronized with critical growth stages (jointing and grain filling), can simultaneously enhance grain yield and quality in this soil type. The optimized combination provides theoretical support and a robust fertilization strategy for green and efficient wheat production in the region.