Increasing temperatures can severely affect wheat (Triticum aestivum L.) production, particularly when it coincides with the grain‐filling period. Heat stress induces rapid senescence resulting in early maturity and shortened grain‐filling period. In this study, the applicability of in vivo chlorophyll fluorescence (Chl‐F) and chlorophyll index to track rate of senescence in flag leaves and spikes exposed to heat stress were investigated. Seven winter wheat varieties were exposed to post‐flowering heat stress using growth chambers [35/15 °C (heat stress) and 25/15 °C (control) day/night] and unique field‐based heat tents (imposed +6 °C higher than ambient). Effective quantum yield of photosystem II (PSII) (QY) was recorded temporally in flag leaves and spikes, and compared with in vitro chlorophyll‐a (Chl‐a) concentration and non‐invasive estimation of chlorophyll and flavonoids index. Time point indicating the start of senescence (change‐point, CP) for QY was advanced by 0–8 and 0–6 d in flag leaves and spikes, respectively, under heat stress. In the chamber experiment, sustained heat stress induced accelerated decline of QY, particularly in wheat cultivars Larry and WB4458. Stronger positive relationship between days to senescence in spikes and thousand kernel weight indicated an extended period of assimilate supply from sink compared to the source tissue, during grain filling. Capturing heat stress‐induced changes in photosynthetic pigments and QY at high temporal frequency presents an effective phenotyping approach for testing genetic diversity in large‐scale field experiments involving different crops.

中文翻译：

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通过光信号跟踪花后热胁迫对冬小麦的影响

温度升高会严重影响小麦（小麦）L.）生产，特别是在谷物充实期的同时。热胁迫导致快速衰老，导致过早成熟和缩短籽粒充实期。在这项研究中，研究了体内叶绿素荧光（Chl-F）和叶绿素指数对跟踪受热胁迫的旗叶和穗状花序衰老速率的适用性。使用生长室[35/15°C（热应力）和25/15°C（日/夜）]和独特的田间高温帐篷（施加+6°），将七个冬小麦品种置于花后热胁迫下C高于环境温度）。暂时记录了旗叶和穗状花序中光系统II（PSII）（QY）的有效量子产量，并将其与体外叶绿素a（Chl-a）浓度以及叶绿素和类黄酮指数的非侵入式估算进行了比较。在热胁迫下，指示旗叶衰老的开始的时间点（变化点，CP）在旗叶和穗状花序中分别提前了0–8和0–6 d。在室内试验中，持续的热胁迫导致QY加速下降，特别是在小麦品种Larry和WB4458中。穗期到衰老的天数与千粒重之间更强的正相关，表明在灌浆过程中，与源组织相比，从源库吸收的同化物供应期延长。在高频率下捕获热胁迫引起的光合色素和QY的变化，是在涉及不同作物的大规模田间试验中测试遗传多样性的有效表型分析方法。在热压力下。在室内试验中，持续的热胁迫导致QY加速下降，特别是在小麦品种Larry和WB4458中。穗期到衰老的天数与千粒重之间更强的正相关，表明在灌浆过程中，与源组织相比，从源库吸收的同化物供应期延长。在高频率下捕获热胁迫引起的光合色素和QY的变化为在涉及不同作物的大规模田间试验中测试遗传多样性提供了一种有效的表型方法。在热压力下。在室内试验中，持续的热胁迫导致QY加速下降，特别是在小麦品种Larry和WB4458中。穗期到衰老的天数与千粒重之间更强的正相关，表明在灌浆过程中，与源组织相比，从源库吸收的同化物供应期延长。在高频率下捕获热胁迫引起的光合色素和QY的变化为在涉及不同作物的大规模田间试验中测试遗传多样性提供了一种有效的表型方法。穗期到衰老的天数与千粒重之间更强的正相关，表明在灌浆过程中，与源组织相比，从源库吸收的同化物供应期延长。在高频率下捕获热胁迫引起的光合色素和QY的变化为在涉及不同作物的大规模田间试验中测试遗传多样性提供了一种有效的表型方法。穗期到衰老的天数与千粒重之间更强的正相关，表明在灌浆过程中，与源组织相比，从源库吸收的同化物供应期延长。在高频率下捕获热胁迫引起的光合色素和QY的变化为在涉及不同作物的大规模田间试验中测试遗传多样性提供了一种有效的表型方法。