Rice is the most important cereal crop in Japan, and therefore the impact of projected climate change on its production and quality has been assessed using rice growth models accounting for the effects of rising temperature and atmospheric CO₂ concentration ([CO₂]) on important growth processes. Recent experimental studies, however, have shown some negative effects of interactions between [CO₂] and temperature on yield and quality of rice which were not accounted for by previous impact assessments. This study examined the importance of [CO₂]×temperature interactions in the nationwide impacts of climate change on grain yield and quality of rice in Japan by 2100. We introduced new functions accounting for the effects of interactions on yield. Then we adopted the acceleration by elevated [CO₂] in the estimation of the occurrence of chalky grains, an indicator of appearance quality of rice. We applied the modified model to Japan at a spatial resolution of 1 km using 10 climate scenarios (5 Global Circulation Models×2 representative concentration pathways [RCPs]) from 1981 to 2100. The effects of the newly introduced negative effects of [CO₂]×temperature were evaluated by comparing simulations with and without the interaction in each scenario. Nationwide production was estimated to decrease by up to 28% and the percentage of white chalky grains to increase up to 16% relative to the previous assessment results, especially in RCP8.5, in which larger increases were projected in both temperature and [CO₂]. The result suggests that the positive effect of elevated [CO₂], which had been expected to offset the negative effect of increased temperature on rice productivity, may be limited in the future, and rice quality degradation may be more severe than predicted previously.

中文翻译：

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考虑到温度和二氧化碳浓度的综合影响，对气候变化对日本稻米产量和品质的影响的估计值进行修订

水稻是日本最重要的谷物作物，因此，使用水稻生长模型评估了预计的气候变化对其产量和质量的影响，其中考虑了温度升高和大气中CO ₂浓度（[CO ₂ ]）对重要作物的影响。成长过程。但是，最近的实验研究表明，[CO ₂ ]和温度之间的相互作用对水稻的产量和品质有一些负面影响，以前的影响评估并未对此做出解释。这项研究探讨了[CO ₂到2100年，气候变化在全国范围内对日本稻米的产量和品质的影响中的]×温度相互作用。我们引入了解释相互作用对产量影响的新函数。然后，我们在估计垩白颗粒的出现时采用了升高的[CO ₂ ]的加速度，这是大米外观质量的指标。我们使用1981年至2100年的10种气候情景（5个全球环流模型×2个代表性浓度路径[RCP]）在1 km的空间分辨率下将修改后的模型应用于日本。新引入的[CO _2]负效应的影响通过比较在每种情况下有无交互作用的模拟来评估]×温度。与先前的评估结果相比，全国范围内的产量估计将减少多达28％，白色垩白颗粒的百分比将增加多达16％，尤其是在RCP8.5中，预计温度和[CO ₂ ]。结果表明，[CO ₂ ]升高的积极作用可能会在将来受到限制，而升高的[CO ₂ ]可能抵消了温度升高对水稻生产的负面影响，而且稻米质量的下降可能比以前的预测更为严重。