The nitrogen application rate (NAR) has a significant effect on the contents of wheat grain protein and its composition. There is still no consensus regarding the appropriate NAR, given the differences in studied conditions and influence of factors such as geographical location, climate, and soil nutrient contents. In this study, 66 papers related to wheat grain protein and its composition published from 1984 to 2021 were selected for meta-analysis in comprehensively evaluating the response of wheat grain protein content and composition to NAR in China. The results reveal that NAR significantly increased total protein content by 9.49–28.6%, gliadin by 9.13–30.5%, glutenin by 12.9–45.4%, albumin by 5.06–15.8%, and globulin by 8.52–24.0% of wheat grain in China, respectively, compared to no nitrogen application. The optimal NAR is 240–300 kg ha⁻¹ when specific planting conditions are not being considered. Under different growing conditions, the NAR that provided the greatest increase in wheat grain protein and its composition varied as follows: 180–240 kg ha⁻¹ in Northwest China and at >100 m altitudes; >300 kg ha⁻¹ in North China and at <100 m altitudes and lower soil base nutrient levels; 240–300 kg ha⁻¹ in Southeast China, with higher soil nutrients levels and for all average annual temperatures and precipitation ranges. In conclusion, the results of the present study reveal that it is feasible to systematically enhance the contents of wheat grain protein and its related fractions by appropriate NAR under different cropping conditions.

No-tillage (NT) has been widely recognized for significantly enhancing crop yield and nitrogen (N) use efficiency in dryland agricultural systems globally. However, in irrigated fields, NT has demonstrated adverse effects on wheat yield, and limited information is available regarding its impact on N uptake and use efficiencies, and grain protein characteristics. Previous studies concluded that drip fertigation (DF) achieved superior yield gain over the conventional N fertilizer broadcasting with flood irrigation (BF) under NT compared to rotary tillage (RT) and intensive tillage (PRT; first plowing followed by rotary tillage). This study measured tissue N concentration, grain protein content and composition, dough processing quality traits, and the activities of N metabolism enzymes in flag leaves and developing grains. The objectives were to (1) evaluate the response of N use traits and grain quality to DF, and (2) elucidate the relationship between gains in yield and N uptake across varying tillage methods. Results revealed that DF significantly increased N uptake by 35.4–38.0%, 22.1–22.2%, and 16.0–16.6% over BF under NT, RT, and PRT, respectively. This boosted N uptake predominantly contributed to enhanced N use efficiency (grain production per unit of total soil mineral and fertilizer N input). Regression analysis indicated that increased N pre-anthesis uptake was the primary driver of yield improvement by DF (r² > 0.99, P < 0.01). Furthermore, NT demonstrated superior improvements by DF in N nutrition index, grain protein content, gliadin content, wet gluten content, and water absorption rate compared to RT and PRT. In conclusion, wheat N use and grain protein under NT responded greater to DF than intensive tillage. Therefore, our findings emphasize that transitioning from conventional water and N management to DF is an effective and practical strategy for enhancing N uptake, achieving high yield, improving N use efficiency, and enriching grain protein content, particularly under NT conditions.

Conventional water and nitrogen (N) management practice in north China, comprising flood irrigation and N fertilizer broadcast (FB), limits sustainable wheat production. Drip fertigation (DF) has been widely adopted in wheat production in recent years and has effectively improved yields. However, the responses of the yield and quality to the N topdressing rate (NTR) under DF are still unclear. This study determined the responses of the wheat yield and quality to NTR under DF, as well as assessing whether DF could synergistically increase the yield and quality. A field experiment was conducted in north China for two seasons (2021–2023) using a split-plot design with three replicates. The main plot used the management practice (FB and DF) and the sub-plot had N treatment (no N applied, and NTRs of 0, 40, 80, 120, and 160 kg ha⁻¹ with 150 kg N ha⁻¹ as basal fertilizer, denoted as N0, T0, T40, T80, T120, and T160, respectively). Our results showed that high and saturated wheat yields (12.08 and 11.46 t ha⁻¹) were obtained under DF at T80, and the highest yields were produced at T160 (11.71 and 11.30 t ha⁻¹) under FB. Compared with FB, the greatest yield increase of 10.4–12.6% was achieved at T80 under DF. A higher spike number due to the increased effective stem percentage and a greater grain weight because of enhanced post-anthesis biomass production (BP_post) explained the improved yield under DF. The enhanced post-anthesis radiation use efficiency (RUE) led to the greater BP_post under DF. The enhanced specific leaf N, antioxidant capacity, and stomatal conductance under DF explained the higher light-saturated photosynthesis rate of flag leaves, which partly led to the increased post-anthesis RUE. NTR higher than 80 kg ha⁻¹ did not enhance the yield, but it significantly improved the gliadin and glutelin contents, thereby leading to a higher total protein content, better gluten characteristics, and superior processing quality. Therefore, drip fertigation is a practical strategy for increasing both yield and quality with reduced water input and appropriate N input in irrigated winter wheat in north China. Applying 80 kg ha⁻¹ of NTR under drip irrigation produces a high yield, but further gain in grain quality needs a higher NTR.

The optimized winter wheat sowing method comprising wide-belt sowing (WBS) can improve the ears number and biomass to increase the grain yield, compared with conventional narrow-drill sowing (NDS). The seed rate and the interaction between the sowing method and seed rate also affect yield formation. However, the effects of the sowing method and seed rate, as well as their interaction on biomass production, particularly the interception of solar radiation (ISR) and radiation use efficiency (RUE), are unclear. A field experiment was conducted for two seasons in southern Shanxi province, China, using a split-plot design with sowing method as the main plot (WBS and NDS) and seed rate as the sub-plot (100–700 m⁻²). Our results showed that while WBS had a significant and positive effect, increasing the yield by 4.7–15.4%, the mechanism differed between seed rates. Yield increase by WBS was mainly attributed to the increase in total biomass resulting from both the promoted pre- and post-anthesis biomass production, except that only the increase in post-anthesis biomass mattered at the lowest seed rate (100 m⁻²). The higher biomass was attributed to the increased ISR before anthesis. After anthesis, the increased ISR contributed mainly to the increased biomass at low seed rates (100 and 200 m⁻²). In contrast, the increased RUE, resulting from the enhanced radiation distribution within canopy and LAI, contributed to the higher post-anthesis biomass at medium and high seed rates (400 to 700 m⁻²). The greatest increases in total biomass, pre-anthesis ISR, and post-anthesis RUE by WBS were all achieved at 500 seed m⁻², thereby obtaining the highest yield. In summary, WBS enhanced grain yield by increasing ISR before anthesis and improving RUE after anthesis, and adopting relatively higher seed rates (400–500 m⁻²) was necessary for maximizing the positive effect of WBS, and thus the higher wheat yield.

Drip fertigation (DF) can improve yield, water use efficiency (WUE), and nitrogen use efficiency (NUE, grain production per unit of the sum of soil inherent mineral N and fertilizer N), as well as reduce the risk of environmental pollution compared with flood irrigation and N fertilizer broadcast (FB). Previously, we showed that DF enhanced the response of the yield to the N topdressing rate (NTR), but the underlying mechanisms associated with the soil N supply, root architecture, and N uptake remain unclear. We conducted a field experiment by testing six N treatments (no N applied, and NTRs of 0, 40, 80, 120, and 160 kg ha⁻¹, denoted as N0, T0, T40, T80, T120, and T160, respectively) under DF and FB from 2021 to 2023. Compared with FB, the NUE and WUE were 4.8–4.9% and 10.0–10.5% higher under DF. The higher NUE was due to an improvement in N uptake efficiency (6.1–7.7%) resulting from the enhanced aboveground N uptake (AGN). The greater AGN under DF was attributed to the higher soil N availability at the soil depth of 0–40 cm. DF decreased the residual soil NO₃⁻-N at a depth of 40–200 cm but increased the NO₃⁻-N at a depth of 0–40 cm. In addition, DF combined with T80 achieved high root length density, surface density, and dry weight density and improved NUE and WUE. DF combined with T80 achieved high yield and efficient utilization of water and N, and the NTR threshold was 61.75–119.50 kg ha⁻¹, in which the production conditions were similar to those of the experimental site. Our results provide a reference for high-efficiency water and N fertilizer usage for irrigated winter wheat production in North China.

Conservation tillage, particularly no tillage (NT), has been recognized as an efficient farming practice, particularly in dryland agriculture, as it significantly enhances crop yields, improves soil health, and contributes to environmental sustainability. However, the influence of NT on winter wheat radiation interception and utilization, biomass, and yield under NT in irrigated fields, especially under drip fertigation, is unclear. A field experiment was carried out for two growing seasons in Shandong province, China, using a split-plot design with the tillage method as the main plot (no tillage, NT; rotary tillage, RT; and first plowing the soil and then conducting rotary tillage, PRT), and water–nitrogen management as the sub-plot (N fertilizer broadcasting and flood irrigation, BF and drip fertigation, DF). Our results showed that DF increased yield by 11.0–28.5%, but the yield response to DF depended on the tillage methods. NT had the highest response in yield of 26.3–28.5%, followed by RT of 14.6–15.1% and PRT of 11.0–11.9%. Both increased grains per ear and ear number, a result of the greater maximum stems number donating to the yield gain by DF under NT. This gain was also due to the substantially promoted post-anthesis biomass (36.7–47.3%), which resulted from the increased interception of solar radiation and radiation use efficiency after anthesis. In addition, the extended post-anthesis duration also benefited biomass and yield. To conclude, our findings underscore the critical need to optimize water and nitrogen management strategies to maximize yield under conservation tillage systems.