Effect of nitrogen application rate on the production of weak-gluten wheat in rice stubble system.

Weak-gluten wheat production prioritizes reduced grain protein content and wet gluten content as quality targets, creating a yield-quality trade-off under nitrogen (N) fertilization. We conducted a two-year field experiment in the rice stubble wheat system of the middle Yangtze River basin to evaluate the effects of six N application rates (0, 45, 90, 135, 180, and 225 kg·hm^-2) on four wheat cultivars (Chuanmai 104, Mianmai 367, Shumai 1671, and Xikemai 8). The results showed that compared to annual variations and cultivar differences, N application exerted stronger influence on spike number per unit area (SA), kernels per spike (KS), SPAD value of penultimate leaf, nitrogen partial factor productivity (PFP_N), protein content, and wet gluten content. Increasing N rates enhanced grain yield, SA, KS, and SPAD value of the upper two leaves (SPADS), and reduced 1000-kernel weight and PFP_N. Agricultural nitrogen use efficiency (AFUE_N) peaked at 90 kg N·hm^-2, whereas protein content and wet gluten content reached minima at 45 kg·hm^-2 before rising with higher N inputs. Yield for any cultivar was not significantly increased in both years when N exceeded 180 kg·hm^-2. Mianmai 367 consistently met weak-gluten quality standards (protein content <12.0%, wet gluten content <24.0%) at N rates ≤135 kg·hm^-2 across both years, achieving grain yield of 6030 kg·hm^-2. Chuanmai 104, Shumai 1671, and Xikemai 8 required stricter N limitations (≤90 kg·hm^-2), with a yield of 5550, 5397, and 5066 kg·hm^-2 respectively. Grain yield showed significant positive correlations with SA and KS, while protein content was positively correlated with SPADS. In summary, the optimal N application range to synchronize yield and weak-gluten quality was 90-135 kg·hm^-2, with Mianmai 367 as the most suitable cultivar. Enhancing spike number per unit area and kernels per spike while reducing SPADS should guide cultivar selection and N management for weak-gluten wheat production.