Warm night frequency has increased steadily in the last years across maize production regions, but high night temperature (HNT) effects on growth, grain yield and maize dry matter allocation (DMA) to different plant organs remain poorly understood. In this study, we aimed to (i) analyse the DMA among reproductive and vegetative organs, (ii) evaluate the individual kernel weight through its determinants, rate and duration of grain filling and (iii) quantify changes in grain yield per plant and its components due to HNT during the postflowering and early grain‐filling period. Field‐grown maize was subjected to HNT induced by shelters during a 15‐ or 30‐day period after silking, encompassing the postflowering period (HNT15) and extending the heating into early grain filling (HNT30), respectively. The HNT was applied from 1900 to 0700 h while control plots remained at ambient night temperature (ANT). Kernel number per plant was decreased under both temperature regimes (i.e., HNT15 and HNT30); however, significant reductions in grain yield were only observed under HNT30. The DMA during the heating period was differentially affected by the duration of heating. While DMA to the stem was likewise reduced by both heating treatments, the partition to the uppermost ear was only reduced under HNT30. Related to the lack of response to HNT treatments of the rate and duration of grain filling, the individual kernel weight was not reduced. The source‐sink ratio was not affected by HNT, meanwhile, the apparent reserve use was significantly reduced under HNT30. Our results demonstrate that the magnitude of HNT effects is subjected to the duration of the heating period, but also depends on the intensity of heating explored across seasons, especially for kernel number and grain yield.

中文翻译：

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玉米在花后和灌浆早期对夜间高温的反应：对产量构成、籽粒生长和干物质分配的影响


近年来，玉米产区的暖夜频率稳步增加，但高夜间温度 (HNT) 对生长、谷物产量和不同植物器官的玉米干物质分配 (DMA) 的影响仍知之甚少。在这项研究中，我们的目的是（i）分析生殖和营养器官之间的DMA，（ii）通过其决定因素、灌浆速率和持续时间来评估单粒重量，以及（iii）量化每株植物的谷物产量及其产量的变化。花后和灌浆早期 HNT 的成分。田间种植的玉米在吐丝后 15 或 30 天期间（包括花后时期）受到庇护所诱导的 HNT 处理（HNT 15 ）并将加热延伸至早期灌浆期（HNT 30 ）， 分别。 HNT 在 1900 至 0700 小时内施用，而对照地块保持在环境夜间温度 (ANT)。在两种温度条件下，每株植物的籽粒数量均减少（即 HNT 15和HNT 30 ）；然而，仅在 HNT 下观察到谷物产量显着下降30 。加热期间的 DMA 受加热持续时间的影响不同。虽然两种加热处理同样减少了茎部的 DMA，但最上面穗的分配仅在 HNT 下减少30 。由于 HNT 处理对籽粒灌浆速度和持续时间缺乏反应，因此单粒重量没有减少。源库比不受HNT影响，同时HNT下表观储量利用显着降低30 。 我们的结果表明，HNT 效应的大小取决于采暖期的持续时间，但也取决于跨季节的采暖强度，尤其是籽粒数量和谷物产量。