Data from: An assessment of wheat yield sensitivity and breeding gains in hot environments

Genetic improvements in heat tolerance of wheat provide a potential adaptation response to long-term warming trends, and may also boost yields in wheat-growing areas already subject to heat stress. Yet there have been few assessments of recent progress in breeding wheat for hot environments. Here, data from 25 years of wheat trials in 76 countries from the International Maize and Wheat Improvement Center (CIMMYT) are used to empirically model the response of wheat to environmental variation and assess the genetic gains over time in different environments and for different breeding strategies. Wheat yields exhibited the most sensitivity to warming during the grain-filling stage, typically the hottest part of the season. Sites with high vapour pressure deficit (VPD) exhibited a less negative response to temperatures during this period, probably associated with increased transpirational cooling. Genetic improvements were assessed by using the empirical model to correct observed yield growth for changes in environmental conditions and management over time. These ‘climate-corrected’ yield trends showed that most of the genetic gains in the high-yield-potential Elite Spring Wheat Yield Trial (ESWYT) were made at cooler temperatures, close to the physiological optimum, with no evidence for genetic gains at the hottest temperatures. In contrast, the Semi-Arid Wheat Yield Trial (SAWYT), a lower-yielding nursery targeted at maintaining yields under stressed conditions, showed the strongest genetic gains at the hottest temperatures. These results imply that targeted breeding efforts help us to ensure progress in building heat tolerance, and that intensified (and possibly new) approaches are needed to improve the yield potential of wheat in hot environments in order to maintain global food security in a warmer climate.

小麦耐热性的遗传改良可为长期变暖趋势提供潜在的适应性应对策略，同时亦可在已受高温胁迫的小麦种植区提升作物产量。然而，目前针对高温环境下小麦育种的近期进展评估仍较为匮乏。本研究借助国际玉米小麦改良中心（International Maize and Wheat Improvement Center, CIMMYT）在76个国家开展的25年小麦试验数据，通过实证建模解析小麦对环境变化的响应，并评估不同环境下、不同育种策略随时间推移的遗传增益。小麦产量对升温最为敏感的时期为籽粒灌浆期——这通常是作物生长季中气温最高的阶段。高水汽压差（vapour pressure deficit, VPD）的试验点在该阶段对温度的负向响应较弱，这可能与蒸腾冷却作用增强有关。本研究通过实证模型校正随时间推移的环境条件与管理措施变化对实测产量增长的影响，以此评估遗传改良效果。经“气候校正”后的产量趋势显示，精英春小麦产量试验（Elite Spring Wheat Yield Trial, ESWYT）作为高产量潜力试验材料，其绝大多数遗传增益均在接近生理最适温度的较凉爽环境中实现，未观测到高温环境下存在遗传增益。与之形成对比的是，半干旱小麦产量试验（Semi-Arid Wheat Yield Trial, SAWYT）这一以胁迫条件下维持产量为目标的低产育苗试验，其最强的遗传增益出现在高温环境中。上述结果表明，针对性的育种工作有助于推进小麦耐热性改良；而为在变暖气候下维持全球粮食安全，我们亟需强化（乃至开发全新的）育种手段，以提升高温环境下的小麦产量潜力。