With abundant thermal resources, there is a long-time span for potential maize sowing in the hot subtropical monsoon region. However, with different sowing dates, maize may be exposed to elevated temperatures at different growth stages. This study aims to understand the impact of sowing date on maize growth and development and yield formation as temperatures increase. A 3-year field experiment was carried out in the typical subtropical monsoon region in China, with 11 sowing dates ranging from mid-March to late June with approximately 10-day intervals (named S1 to S11), and three main commercial varieties were included to validate the impact of sowing date. Following delayed sowing, maize plants were exposed to increased temperatures during the emergence (VE) to silking (R1) stages. Maize plants of the three varieties exhibited similar responses to delayed sowing dates in terms of growth, development, and yield performance. Vegetative growth was accelerated, while the anthesis-silking interval (ASI) and the vegetative-to-reproductive transition, that is, the interval of V12 (twelfth leaf) to R1 stages, were prolonged. The grain yield gradually decreased and reached a minimum at approximately S8-S10 (varied among varieties), which was in accordance with the decreased grain number. Further analyses revealed that the decreased grain number and yield were associated with a prolonged V12-R1 interval with delayed sowing. The duration of V12-R1 was significantly positively correlated with the maximum and minimum temperatures within a day, suggesting that the V12-R1 interval could be a parameter for evaluation of heat’s impact on yield formation. Grain weight decreased as the temperature of the R1-R6 stage rose before S8 but increased as the temperature dropped after S8. Inconsistently, biomass accumulation, leaf area, and plant and ear height first increased and then decreased before and after S3-S6, respectively. Delayed sowing in hot subtropical monsoon regions exposes maize plants to elevated temperatures, leading to accelerated vegetative and reproductive growth but a prolonged vegetative-to-reproductive transition, and suppresses yield by reducing grain number and/or weight, resulting the yield decreased with the delayed sowing. By demonstrating the impacts of high temperature with different sowing dates on the phenology, morphology, and yield formation of maize, this study provides a basis for improving maize yield in practical production by optimizing the sowing date.

中文翻译：

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播期对玉米的影响：亚热带季风区物候、形态和产量形成

亚热带季风区热能资源丰富，玉米播种期长。然而，由于播种日期不同，玉米在不同的生长阶段可能会暴露在高温下。本研究旨在了解随着气温升高，播种日期对玉米生长发育和产量形成的影响。在我国典型的亚热带季风区进行了为期3年的田间试验，从3月中旬至6月下旬，间隔10天左右的11个播期（命名为S1至S11），纳入了3个主要商品品种。验证播种日期的影响。延迟播种后，玉米植株在出苗（VE）到吐丝（R1）阶段暴露在升高的温度下。三个品种的玉米植株在生长、发育和产量表现方面对延迟播种期表现出相似的反应。营养生长加速，同时开花吐丝间隔（ASI）和营养向生殖转变，即V12（第十二叶）到R1阶段的间隔延长。籽粒产量逐渐下降，并在S8-S10左右达到最低值（因品种不同），与籽粒数的减少相一致。进一步分析表明，籽粒数和产量下降与V12-R1间隔延长和延迟播种有关。 V12-R1持续时间与一天内最高、最低气温显着正相关，表明V12-R1区间可作为评价热量对产量形成影响的参数。在S8之前，粒重随着R1-R6阶段温度的升高而降低，但随着S8之后温度的降低而增加。不一致的是，生物量积累、叶面积、株高和穗高分别在S3-S6前后先增加后减少。在炎热的亚热带季风地区，推迟播种会使玉米植株暴露在高温下，导致营养和生殖生长加速，但营养到生殖的转变时间延长，并通过减少籽粒数量和/或重量来抑制产量，导致产量随着推迟播种而下降。播种。本研究通过论证不同播期高温对玉米物候、形态及产量形成的影响，为实际生产中通过优化播期提高玉米产量提供依据。