The impact of grain yield on post-silking N uptake (PostN) in maize has been a major focus of previous studies, although results are mixed as to the direction and magnitude of the relationship between these two variables. The objective of this study was to understand how grain yield and other plant traits interact with exogenous N and water availability to regulate PostN in maize. In a greenhouse experiment, maize was subjected to high or low levels of N and water supply pre-silking during vegetative growth, which created large variations in source and sink components such as ear size and leaf area. Notably, these large differences in source and sink components were generated not by cutting off plant organs but instead by relying on maize response to vegetative-stage N and water stress. These plants were then subject to high and low levels of N and water supply post-silking, and the relationship between plant traits and PostN was characterized. Final grain yield was irrevocably reduced in the treatments where pre-silking water stress occurred compared to the well-watered pre-silking treatments (30 g plant-1-1 vs. 106 g plant-1). Because of the reduced ear sink strength in the treatments experiencing pre-silking water stress, post-silking biomass (PostBM) and PostN accumulated in vegetative organs. This resulted in greater PostN at maturity in the lower yielding treatments when post-silking water and/or N stress occurred (1.1 vs. 0.6 g N plant-1). Due to the shift in assimilate and N partitioning towards vegetative organs, leaf CER and root dry weight during grain-fill were better maintained in the lower yielding treatments. We conclude that while biomass accumulation (PostBM) regulates PostN, under post-silking N or water stress, shifting sink organs from the grain to vegetative structures increases PostN by improving vegetative organ function and enhancing post-silking source-sink ratios.

中文翻译：

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哪些植物性状与水分和/或氮胁迫下玉米的落丝后氮吸收最密切相关？

谷物产量对玉米上丝后吸氮 (PostN) 的影响一直是先前研究的主要焦点，尽管关于这两个变量之间关系的方向和大小的结果不一。本研究的目的是了解谷物产量和其他植物性状如何与外源 N 和水分可用性相互作用以调节玉米中的 PostN。在温室试验中，玉米在营养生长过程中受到高或低水平的氮和水供应的影响，这会导致源和汇组成部分（例如穗大小和叶面积）发生很大变化。值得注意的是，源和汇成分的这些巨大差异不是通过切断植物器官产生的，而是依赖于玉米对营养阶段氮和水分胁迫的反应。然后对这些植物进行高水平和低水平的施肥后施氮和供水，并表征植物性状与后施氮之间的关系。与浇水良好的预撒尿处理（30 g 植物 1-1 与 106 克植物 1）相比，在出现预撒水胁迫的处理中，最终谷物产量不可逆转地降低。由于在经历预蚕丝水分胁迫的处理中耳槽强度降低，蚕丝后生物量 (PostBM) 和 PostN 在营养器官中积累。这导致在发生后施水和/或氮胁迫（1.1 与 0.6 g N 植物-1）时，在低产处理中成熟时更大的 PostN。由于同化物和 N 分配向营养器官的转移，籽粒灌浆期间的叶片 CER 和根干重在低产处理中得到更好的保持。