High temperatures and increasing CO₂ concentrations are a major threat to global wheat (Triticum aestivum L.) production, demanding the development of heat-tolerant wheat cultivars. Plant physiological traits are potential surrogates for evaluating genetic variation for crop stress tolerance. This research evaluated 23 Australian wheat cultivars and two breeding lines for heat-tolerance by characterising the associated physiological traits. The interactive effects of heat-stress and elevated CO₂ were studied under controlled greenhouse conditions and delayed sowing in the field with exposure to higher temperature. Physiological changes, pollen viability and grain yield were assessed. A significant correlation was observed between physiological and agronomical traits under high temperature at 35°C and elevated CO₂ at 800 µl L⁻¹, providing evidence of adaptation to high temperatures in some genotypes. Variation in stomatal conductance, transpiration rate, canopy temperature, leaf chlorophyll and photosynthesis were associated with maintenance of pollen viability and grain yield at high temperatures. Of the genotypes assessed, seven were classified as heat tolerant at both ambient and elevated CO₂ and nine were heat susceptible while the remainder showed a variable response to CO₂ at high temperatures. Field data confirmed the heat responses of the most heat-tolerant and susceptible genotypes. The heat tolerant genotypes identified are candidates for further breeding and selection to improve adaptation to a changing climate.

中文翻译：

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用于评估高 CO2 条件下澳大利亚春小麦品种耐热性的生理性状

高温和不断增加的CO ₂浓度是全球小麦（Triticum aestivum L.）生产的主要威胁，需要开发耐热小麦品种。植物生理性状是评估作物抗逆性遗传变异的潜在替代指标。这项研究通过表征相关的生理特征评估了 23 个澳大利亚小麦品种和两个育种系的耐热性。_{热应激与CO 2}升高的交互作用在受控温室条件下进行研究，并在暴露于较高温度的田间延迟播种。评估了生理变化、花粉活力和谷物产量。在 35°C 高温和800 µl L ^{-1升高的 CO} ₂条件下，生理和农艺性状之间观察到显着相关性，为某些基因型适应高温提供了证据。气孔导度、蒸腾速率、冠层温度、叶片叶绿素和光合作用的变化与高温下花粉活力和谷物产量的维持有关。_{在评估的基因型中，有 7 种在环境和高 CO 2}条件下均被归类为耐热型九个对热敏感，而其余的在高温下对 CO ₂表现出可变的响应。现场数据证实了最耐热和最易感基因型的热反应。确定的耐热基因型是进一步育种和选择的候选者，以提高对气候变化的适应能力。