Application of nitrogen (N) fertilizer usually increases grain yield (GY) and grain protein content (GPC) simultaneously. But low GPC is desirable in soft wheat (Triticum aestivum L.). To break the unexpected link, we investigated the combined effects of reduced N rate, increased plant density on GY, nitrogen agronomic efficiency (NAE) and GPC targeting biscuit-making of two soft wheat cultivars. The field experiments involved four N rates (240, 180, 120 and 0 kg N ha⁻¹) and three plant densities (180, 240 and 300 × 10⁴ plants ha⁻¹). Reducing N rate improved grain quality for biscuit-making and NAE in soft wheat, but resulted in lower dry matter accumulation and caused a significant GY loss. With the N rate ranged from 240 to 0 kg N ha⁻¹, GY loss of 16.28–18.54 kg ha⁻¹ was observed for every 1 kg N ha⁻¹ reduction. Increasing plant density significantly enhanced the population dry matter accumulation and partially compensated for GY loss caused by reduced N via increasing the number of effective ears, meanwhile further improved grain quality and NAE. When the plant density increased from 180 to 300 × 10⁴ plants ha^–1, increasing 1.0 × 10⁴ plants ha^–1 led to an increment in average GY of 4.79, 6.78 and 3.98 kg ha^–1 under 180, 120 and 0 kg N ha⁻¹, respectively. The reduction of 1 kg N ha^–1 was replaced by increasing app. 2.40–4.09 × 10⁴ plants ha^–1 to maintain same GY. The decrease in GPC by the combination of reduced N rate and increased plant density was mainly attributed to the variations in pre-anthesis accumulated N in vegetative organs as well as the whole plant. Moreover, reducing N rate showed a more remarkable effect on GPC than increasing plant density, and their interaction effect was significant. Our study therefore provided an agronomic approach to balance GY and GPC targeting biscuit-making in soft wheat production by the combination of low N rate and high plant density.

氮肥的施用通常会同时增加谷物产量（GY）和谷物蛋白质含量（GPC）。但是低GPC在软质小麦（Triticum aestivum L.）中是理想的。为了打破意料之外的联系，我们研究了降低氮肥施用量，增加植物密度对GY，氮素农艺效率（NAE）和GPC靶向两种软质小麦饼干制造的综合影响。田间试验涉及四种氮素浓度（240、180、120和0 kg N ha ^-1）和三种植物密度（180、240和300×10 ⁴种植物ha ^-1）。降低氮含量可以改善软麦的饼干生产和NAE的籽粒品质，但导致干物质积累降低，并导致显着的GY损失。当氮含量为240至0 kg N ha ^-1时，每减少1 kg N ha ^-1，GY损失为16.28-18.54 kg ha ^-1。增加植物密度显着提高了群体干物质的积累，并通过增加有效穗数来部分补偿了氮减少所引起的GY损失，同时进一步改善了谷物品质和NAE。当植物密度从180增加到300×10 ⁴植物ha ^–1时，增加1.0×10 ⁴植物ha ^–1导致平均GY分别在180、120和0 kg N ha ^-1下增加4.79、6.78和3.98 kg ha ^–1。减少的1 kg N ha ^–1被增加的app所代替。2.40–4.09×10 ⁴公顷公顷^–1保持相同的GY。氮素含量降低和植物密度增加共同导致GPC降低主要是由于花前营养素在植物以及整个植物中积累的氮含量的变化所致。此外，降低氮肥施用量比增加植物密度对GPC有更显着的影响，而且它们之间的相互作用也很显着。因此，我们的研究提供了一种农艺学方法，可通过低氮肥和高植物密度的组合来平衡软麦生产中饼干生产的GY和GPC。