The United States (U.S.) is the world's 4th largest rice exporter and challenges associated with extreme heat and water availability may pose a threat to future productivity. Forecasts from multiple CMIP6 climate models were linked with geospatial data and a version of the ORYZA crop model, revised with updates to phenology, heat stress, gas exchange, and energy balance components, to evaluate yield and water use efficiency (WUE) in response to future climate projections using four region specific heat tolerant versus sensitive rice cultivars. Rising temperatures were projected to reduce yield by 12–25 % and 22–41 % for the 2040s and 2070s, respectively. California and the north Mississippi Delta were the most vulnerable regions. Elevated atmospheric CO was projected to compensate for 18–42 % of yield losses in the 2070s and could alleviate most negative impacts of rising temperatures on heat-tolerant crop varieties. Heat-sensitive cultivars still experienced 1 to 5 % yield reductions during the same periods. The cultivar distinction was particularly evident in 2070s under SSP585 scenario, in which yields for the heat tolerant cultivars were 12 % greater than heat sensitive ones. A significant portion of predicted yield loss was attributed to reduced spikelet fertility due to heat stress during anthesis. Thus, breeding for heat tolerance and high-yield traits is a potential strategy for climate adaptation. Without elevated CO, WUE is likely to decline by 14–25 % for 2040, and 23–42 % for the 2070s. These WUE reductions were mitigated -3 % to 7 % and -4 % to 8 % for the 2040s and 2070s under elevated CO. This model-based effort provides unique spatial assessments regarding projected climate impacts on potential rice yield and water use and highlights the need for integrating crop genetic and region-specific adaptation strategies to maintain sustainable rice production.

中文翻译：

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量化气候变化和极端高温对美国水稻的影响


美国是世界第四大稻米出口国，与极端高温和水资源供应相关的挑战可能会对未来的生产力构成威胁。来自多个 CMIP6 气候模型的预测与地理空间数据和 ORYZA 作物模型版本相关联，并根据物候、热应激、气体交换和能量平衡组成部分进行了更新，以评估产量和水分利用效率 (WUE)，以响应使用四个地区特定的耐热与敏感水稻品种对未来气候进行预测。预计 2040 年代和 2070 年代气温上升将分别导致产量减少 12-25% 和 22-41%。加利福尼亚州和密西西比三角洲北部是最脆弱的地区。预计大气二氧化碳浓度升高将弥补 2070 年代 18-42% 的产量损失，并可减轻气温升高对耐热作物品种的大部分负面影响。同期，热敏感品种的产量仍下降了 1% 至 5%。品种差异在 2070 年代在 SSP585 情景下尤其明显，其中耐热品种的产量比热敏感品种高 12%。预计产量损失的很大一部分是由于开花期间的热应激导致的小穗育性降低。因此，耐热性和高产性状的育种是适应气候的潜在策略。如果二氧化碳不增加，WUE 可能会在 2040 年下降 14-25%，在 2070 年代下降 23-42%。在二氧化碳浓度升高的情况下，2040 年代和 2070 年代 WUE 的减少幅度分别为 -3% 至 7% 和 -4% 至 8%。 这项基于模型的工作提供了关于预计气候对潜在水稻产量和用水的影响的独特空间评估，并强调需要整合作物遗传和特定区域的适应策略以维持可持续的水稻生产。