ABSTRACT: High temperatures occurring during flowering and early grain filling substantially decrease cereal yields. Drawing on accumulated evidence showing that, compared to air temperature (Ta), crop canopy temperature (Tc) better explains observed yield reductions caused by heat stress, we evaluated the usefulness of Tc versus Ta in designing high-temperature indicators for agrometeorological services, including crop monitoring and forecasting. The hot and dry environment of Sudan provides an ideal testbed. Tc was derived from the combined simulation of a crop model and a land surface model. Based on regressions linking the high-temperature indicators with irrigated wheat yield variations in 3 regions of Sudan over the last half-century, we found that using phenological periods rather than months for the wheat season (November to February), and using Tc rather than Ta, more effectively tracks the adverse effects of high temperature on yield during the key periods. The Tc-based indicators calculated for the key phenological periods have more robust multi-region applicability than the Ta-based indicators calculated for months and season, although they do not necessarily outperform the region-specific indicators in terms of explanatory power. We determined that the key periods were the vegetative growth period for the relatively cool region, and the reproductive growth period for the relatively hot regions. These findings suggest that agrometeorological services at the national and global levels should adopt Tc-based indicators, which will ultimately help players in global food systems adapt to climate change by preparing for wheat supply disruptions due to high-temperature extremes.

中文翻译：

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捕捉热胁迫对产量影响的高温指标：苏丹干热环境下灌溉小麦的经验教训

摘要：开花期和灌浆早期出现的高温会显着降低谷物产量。根据积累的证据表明，与气温 (Ta) 相比，作物冠层温度 (Tc) 更好地解释了观察到的由热胁迫引起的产量下降，我们评估了 Tc 与 Ta 在设计农业气象服务高温指标方面的有用性，包括作物监测和预报。苏丹炎热干燥的环境提供了一个理想的试验台。Tc 源自作物模型和地表模型的组合模拟。基于过去半个世纪苏丹 3 个地区的高温指标与灌溉小麦产量变化相关联的回归，我们发现使用物候期而不是小麦季节（11 月至 2 月）的月份，并且使用Tc而不是Ta，更有效地跟踪关键时期高温对产量的不利影响。针对关键物候期计算的基于 Tc 的指标比基于月份和季节计算的基于 Ta 的指标具有更强的多区域适用性，尽管它们在解释力方面不一定优于区域特定指标。我们确定关键时期为相对凉爽地区的营养生长期和相对炎热地区的生殖生长期。这些发现表明，国家和全球层面的农业气象服务应采用基于 Tc 的指标，这将最终帮助全球粮食系统的参与者通过为极端高温导致的小麦供应中断做好准备来适应气候变化。