Shade stress severely limits plant growth and crop productivity. This study investigated the relationship between shade stress and nitrogen (N) accumulation in maize at different growth stages. Field experiments were conducted in 2015 and 2016 with three shading treatments: from emergence stage (VE) to physiological maturity (R6) (whole‐season shade), from six‐leaf (V6) to tassel stage (VT) (midseason shade), and from VT to R6 (late‐season shade). Ambient sunlight was used as control (CK). Two hybrids, Zhengdan958 (ZD958) and Denghai 605 (DH605), were used. This study focused on accumulation and partition of dry matter (DM) and N based on the above treatments. Shading reduced DM and N accumulation of maize, which decreased yield. In addition, ¹⁵N stable isotope tracing revealed that shading disrupted N accumulation, partitioning, and remobilization in different organs. The contents of grain ¹⁵N in whole‐season shade, midseason shade, and late‐season shade from ZD958 decreased by 60, 28, and 50%, respectively, compared with those in CK, and DH605 decreased by 70, 32, and 51%, respectively. Our results indicate that yield decline can be mainly attributed to DM and that N accumulation and remobilization were disrupted by shading at different maize growth stages. Shading during the vegetative stage and reproductive stage reduced N accumulation, and shading during the reproductive stage mainly promoted N transport from other organs to grain, which mitigated some of the effects of reduced N absorption.

中文翻译：

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遮荫胁迫降低了玉米籽粒产量，干物质和氮积累

阴影胁迫严重限制了植物的生长和作物的生产力。本研究调查了不同生育阶段玉米的遮荫胁迫与氮（N）积累之间的关系。在2015年和2016年进行了三种遮光处理的田间试验：从出苗阶段（VE）到生理成熟期（R6）（整个季节的阴影），从六叶（V6）到流苏阶段（VT）（季节的中间阴影），从VT到R6（后期阴影）。周围的阳光用作对照（CK）。使用了两个杂种，郑丹958（ZD958）和登海605（DH605）。这项研究集中在基于上述处理的干物质（DM）和氮的积累和分配上。遮荫减少了玉米的DM和N积累，从而降低了产量。另外¹⁵N稳定同位素示踪显示，遮光破坏了N在不同器官中的积累，分配和迁移。与CK相比，ZD958的全季，中期和后期的¹⁵ N籽粒含量分别降低了60％，28％和50％，DH605分别降低了70％，32％和51％ ％， 分别。我们的结果表明，产量下降可能主要归因于DM，而不同玉米生长阶段的遮荫破坏了N的积累和迁移。营养期和生殖期的遮荫减少了氮的积累，而生殖期的遮荫主要促进了氮从其他器官向谷物的转运，从而减轻了减少氮吸收的某些影响。