Changing climate conditions are influencing quality and yield of the United States rice (Oryza sativa L.) export industry. The occurrence of high heat episodes, along with rising atmospheric carbon dioxide (CO₂), is of particular concern for as-yet uncharacterized hybrid varieties. A popular rice hybrid was grown in soil-plant-atmosphere-research (SPAR) chambers under two CO₂ levels (450 or 740 ppm) and subjected to one of three day/night temperature regimes during anthesis and grainfill: a control temperature (T) (0C) of 28/22°C, and a +4° (4C) or +8°C (8C) increase. There was little difference in biomass between 0 and 4C levels; however, yields at the 8C level declined by over 50%, by about 28 or 34 g plant⁻¹°C⁻¹ for ambient or elevated CO₂ grown rice, respectively. There was little difference in fraction of biomass allocated among leaf, stem or panicle at 0 or 4C, but the proportion declined by about 31% to the panicles at 8C. Total productive tiller numbers and grainfill percentages were similar across CO₂ levels at each T treatment such that yield declines were associated primarily with a decrease in grain number and mass. Slightly higher values for yield and harvest index were observed under elevated CO₂ at the 3 T levels which was attributed to an average 10 mg increase in single grain weight. An interaction of CO₂ and T on chalk content was observed, with expression at the +4°C treatment 11% higher for elevated versus ambient CO₂; however, chalk expression was similar for CO₂ levels at the +8°C treatment. Breeding efforts associated with climate resiliency should consider traits associated with hybrid vigor as well as high temperature resistance for grain sterility and quality factor responses.

不断变化的气候条件正在影响美国大米（Oryza sativa L.）出口行业的质量和产量。高温事件的发生以及大气中二氧化碳（CO ₂）的上升，对于尚未表征的杂交品种来说尤其令人担忧。一种流行的水稻杂交种在土壤-植物-大气研究 (SPAR) 室中在两种 CO ₂水平（450 或 740 ppm）下生长，并在开花和灌浆期间经受三个昼夜温度状态之一：控制温度（T ) (0C) 为 28/22°C，并增加 +4° (4C) 或 +8°C (8C)。0和4C水平之间的生物量差异很小；然而，8C 水平的产量下降了 50% 以上，约 28 或 34 克植物^-1 °C ^-1分别用于常温或高 CO ₂生长的水稻。0℃或4℃时叶、茎、穗间生物量分配比例差异不大，但8℃时向穗部分配的比例下降约31%。_{在每个 T 处理的 CO 2}水平上，总生产性分蘖数和籽粒填充百分比相似，因此产量下降主要与籽粒数量和质量的减少有关。_{在 3 T 水平的 CO 2}升高的情况下，观察到产量和收获指数的值略高，这归因于单粒重平均增加 10 mg。_{观察到 CO 2}和 T 对白垩含量的相互作用，在 +4°C 处理下，升高的 CO 浓度比环境 CO 高 11%₂ ; 然而，在 +8°C 处理时，CO ₂水平的粉笔表达相似。与气候适应力相关的育种工作应考虑与杂交活力相关的性状以及谷物不育和品质因子响应的耐高温性。