Optimizing sowing patterns in winter wheat can reduce N2O emissions and improve grain yield and NUE by enhancing N uptake.

Increasing nitrogen (N) input is essential to satisfy the rising global wheat demand, but this increases nitrous oxide (N2O) emissions, thereby exacerbating global climate change. Higher yields accompanied by reduced N2O emissions are essential to synergistically reduce greenhouse warming and ensure global food security. In this study, we conducted a trial using two sowing patterns (conventional drilling sowing [CD] and wide belt sowing [WB], with seedling belt widths of 2-3 and 8-10 cm, respectively) with four N rates (0, 168, 240, and 312 kg ha-1, hereafter N0, N168, N240, and N312, respectively) during the 2019-2020 and 2020-2021 growing seasons. We investigated the impacts of growing season, sowing pattern, and N rate on N2O emissions, N2O emissions factors (EFs), global warming potential (GWP), yield-scaled N2O emissions, grain yield, N use efficiency (NUE), plant N uptake and soil inorganic N concentrations at jointing, anthesis, and maturity. The results showed that sowing pattern and N rate interactions influenced the N2O emissions markedly. Compared to CD, WB significantly reduced cumulative N2O emissions, N2O EFs, GWP, and yield-scaled N2O emissions for N168, N240, and N312, with the largest reduction seen at N312. Furthermore, WB markedly improved plant N uptake and reduced soil inorganic N compared to CD at each N rate. Correlation analyses indicated that WB mitigated the N2O emissions at various N rates mainly through efficient N uptake and reduced soil inorganic N. The highest grain yield occurred under a combination of WB and N312, under which the yield-scaled N2O emissions were equal to the local management (sowing with CD at N240). In conclusion, WB sowing could synergistically decrease N2O emissions and obtain high grain yields and NUEs, especially at higher N rates.

Chain Terminators and Glutathione Weaken Wheat Dough under Excess Nitrogen Input.

An excessive nitrogen (N) supply may weaken dough due to an imbalance between N and sulfur (S) in the grains. However, the mechanism underlying the weakening effect of excessive N supply has yet to be fully elucidated. In this study, we evaluated the effect of the N rate × S rate interaction on the ratio of N to S (N/S ratio), grain protein concentration, amount and composition of protein fractions, and dough properties of a bread wheat cultivar. The concentrations of glutathione and modified gliadins with an odd number of cysteine residues (potential chain terminators for glutenins) were also examined. The results revealed that the weakening effect of excess N input is closely associated with an increased gliadin/glutenin ratio, reduced low-molecular-weight glutenin subunit concentrations, and the degree of polymerization of glutenin. More importantly, we found that the increased concentrations of glutathione and chain terminators in grains are involved in the modification of the polymerization degree in glutenins.

Optimized seeding rate and nitrogen topdressing ratio for simultaneous improvement of grain yield and bread-making quality in bread wheat sown on different dates.

BACKGROUND: Sowing date, seeding rate, and nitrogen (N) topdressing ratio have strong effects on grain yield (GY) and bread-making quality (BQ) in bread wheat. Simultaneous improvement in GY and BQ in bread wheat has long been a challenge due to the inverse relationship between GY and grain protein concentration (GPC). In this study, we investigated whether the GY and BQ of bread wheat sown on different dates could be improved simultaneously by optimizing the seeding rate and the N topdressing ratio. RESULTS: Delaying sowing beyond a certain period led to decreases in both GY and BQ. Optimizing the seeding rate and N topdressing ratio enhanced the N uptake during pre- and post-anthesis, as well as N remobilization during grain filling for all wheat plants sown on different dates, thereby increasing the GPC and the total N per grain (Ntot ). Consequently, grain protein composition was improved, resulting in an increased glutenin/gliadin ratio, sodium dodecyl sulfate-insoluble glutenin/total glutenin (i.e., glutenin polymerization index), and high-molecular-weight glutenin subunit/ low-molecular-weight glutenin subunit (HMW-GS/LMW-GS) ratio. Increased GPC and improved grain protein composition enhanced BQ. CONCLUSION: The mechanism underlying simultaneous improvement in GY and GPC as well as Ntot was the greater increase in N accumulation in grains per unit area relative to increases in GY, or total grain number per unit area. The GY and BQ can be improved simultaneously regardless of sowing date by optimizing the seeding rate and N topdressing ratio via enhanced N uptake and N remobilization into grains. © 2021 Society of Chemical Industry.

[Interactive effects of irrigation regime and planting density on grain yield and water use efficiency in winter wheat]. / 灌水量与密度互作对冬小麦籽粒产量和水分利用效率的影响.

To get an optimal irrigation regime and planting density for simultaneous improvement of grain yield (GY) and water use efficiency (WUE) in winter wheat, we examined the responses of 'Tainong 18' (with bigger ears) and 'Shannong 22' (with medium-sized ears) under four irrigation regimes, including 0, 45, 60, and 75 mm. Those two cultivars were planted at four densities: Tainong 18 at 135×104, 270×104, 405×104, and 540×104 plants·hm-2 and Shannong 22 at 90×104, 180×104, 270×104, and 360×104 plants·hm-2. The interactive effects of irrigation regimes and plant densities on GY, water consumption characteristics, and WUE were investigated. The results showed that GY, evapotranspiration, soil water consumption, and WUE were significantly affected by irrigation regime, plant density, and their interaction. The optimal irrigation regime was 45 mm for both cultivars, while the optimal plant density was 405×104 plants·hm-2 for Tainong 18 and 270×104 plants·hm-2 for Shannong 22, as indicated by the highest GY, the lowest ratio of soil evaporation to evapotranspiration after jointing, and higher WUE and the ratio of soil water consumption below 1 m to total soil water consumption. The rational combination of plant density and irrigation could reduce unnecessary water consumption and improve WUE.