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) 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), 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. Agricultural nitrogen use efficiency (AFUE) peaked at 90 kg N·hm, whereas protein content and wet gluten content reached minima at 45 kg·hm before rising with higher N inputs. Yield for any cultivar was not significantly increased in both years when N exceeded 180 kg·hm. Mianmai 367 consistently met weak-gluten quality standards (protein content <12.0%, wet gluten content <24.0%) at N rates ≤135 kg·hm across both years, achieving grain yield of 6030 kg·hm. Chuanmai 104, Shumai 1671, and Xikemai 8 required stricter N limitations (≤90 kg·hm), with a yield of 5550, 5397, and 5066 kg·hm 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, 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.