Warming nights are correlated with declining wheat growth and yield. As a key determinant of plant biomass, respiration consumes O2 as it produces ATP and releases CO2 and is typically reduced under warming to maintain metabolic efficiency. We compared the response of respiratory O2 and CO2 flux to multiple night and day warming treatments in wheat leaves and roots, using one commercial (Mace) and one breeding cultivar grown in controlled environments. We also examined the effect of night warming and a day heatwave on the capacity of the ATP-uncoupled alternative oxidase (AOX) pathway. Under warm nights, plant biomass fell, respiratory CO2 release measured at a common temperature was unchanged (indicating higher rates of CO2 release at prevailing growth temperature), respiratory O2 consumption at a common temperature declined, and AOX pathway capacity increased. The uncoupling of CO2 and O2 exchange and enhanced AOX pathway capacity suggest a reduction in plant energy demand under warm nights (lower O2 consumption), alongside higher rates of CO2 release under prevailing growth temperature (due to a lack of down-regulation of respiratory CO2 release). Less efficient ATP synthesis, teamed with sustained CO2 flux, could thus be driving observed biomass declines under warm nights.

中文翻译：

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小麦呼吸氧气消耗量随着夜间变暖而下降，同时呼吸二氧化碳损失增加和生物量减少

变暖的夜晚与小麦生长和产量下降有关。作为植物生物量的关键决定因素，呼吸作用会消耗 O2，因为它会产生 ATP 并释放 CO2，并且通常会在变暖时减少以保持代谢效率。我们使用一种商业（Mace）和一种在受控环境中生长的育种品种，比较了呼吸氧气和二氧化碳通量对小麦叶和根的多次昼夜升温处理的响应。我们还检查了夜间变暖和白天热浪对 ATP 非耦合替代氧化酶 (AOX) 途径能力的影响。在温暖的夜晚，植物生物量下降，在普通温度下测量的呼吸 CO2 释放没有变化（表明在主要生长温度下 CO2 释放率更高），在普通温度下呼吸 O2 消耗量下降，和 AOX 通路容量增加。CO2 和 O2 交换的解耦以及 AOX 途径能力的增强表明在温暖的夜晚（较低的 O2 消耗）下植物能量需求减少，同时在主要生长温度下 CO2 释放率更高（由于缺乏对呼吸 CO2 的下调发布）。因此，较低效率的 ATP 合成与持续的 CO2 通量相结合，可能会导致在温暖的夜晚观察到的生物量下降。