Understanding Dry Matter and Nitrogen Accumulation with Time-Course for High-Yielding Wheat Production in China

Understanding the time-course of dry matter (DM) and nitrogen (N) accumulation in terms of yield–trait relationships is essential to simultaneously increase grain yield and synchronize N demand and N supply. We collected 413 data points from 11 field experiments to address patterns of DM and N accumulation with time in relation to grain yield and management of winter wheat in China. Detailed growth analysis was conducted at the Zadok growth stages (GS) 25 (regreening), GS30 (stem elongation), GS60 (anthesis), and GS100 (maturity) in all experiments, including DM and N accumulation. Grain yield averaged 7.3 Mg ha−1, ranging from 2.1 to 11.2 Mg ha−1. The percent N accumulation was consistent prior to DM accumulation, while both DM and N accumulation increased continuously with growing time. Both the highest and fastest DM and N accumulations were observed from stem elongation to the anthesis stage. Significant correlations between grain yield and DM and N accumulation were found at each of the four growth stages, although no positive relationship was observed between grain yield and harvest index or N harvest index. The yield increase from 7–9 Mg ha−1 to >9 Mg ha−1 was mainly attributed to increased DM and N accumulation from stem elongation to anthesis. Although applying more N fertilizer increased N accumulation during this stage, DM accumulation was not improved, indicating that N fertilizer management and related agronomic management should be intensified synchronously across the wheat growing season to simultaneously achieve high yields and match N demand and N supply.

明晰干物质（dry matter，DM）与氮素（nitrogen，N）积累的时间进程及其与产量-性状的关联，对同步提升籽粒产量、协调氮素供需关系至关重要。本研究从11组田间试验中收集了413组有效数据，旨在解析我国冬小麦干物质与氮素积累随时间的变化规律，及其与籽粒产量和栽培管理的关联。所有试验均在扎多克生育期（Zadok growth stages，GS）25（返青期）、GS30（拔节期）、GS60（开花期）与GS100（成熟期）开展了详细的生长分析，测定指标涵盖干物质积累量与氮素积累量。供试材料的籽粒产量平均值为7.3 Mg·ha⁻¹，变幅范围为2.1~11.2 Mg·ha⁻¹。在干物质积累启动前，氮素积累占比保持稳定；而干物质与氮素积累量均随生育进程持续提升。干物质与氮素积累的最高水平及最快速率均出现在拔节期至开花期阶段。在四个观测生育时期均观测到籽粒产量与干物质、氮素积累量存在显著相关性，但籽粒产量与收获指数、氮收获指数之间未呈现显著正相关关系。当籽粒产量从7~9 Mg·ha⁻¹提升至>9 Mg·ha⁻¹时，其增产效应主要归因于拔节期至开花期干物质与氮素积累量的增加。尽管增施氮肥可提升该阶段的氮素积累量，但并未改善干物质积累水平，这表明需在小麦全生育期同步强化氮肥管理与相关农艺措施，以实现高产目标并协调氮素供需平衡。