The stable isotopic compositions of carbon (δ13C) and oxygen (δ18O) in rice are often used to confirm its authenticity. The gelatinization temperature is a crucial factor in alcoholic fermentation. However, little is known about the isotopic and thermal responses of rice to climate change. We show that in sake rice grown annually in the same paddy field from 1994 to 2013, the δ13C (-27.4‰ to -25.9‰) and δ18O values (20.4‰ to 27.0‰) correlated negatively with the mean daily minimum air temperature and precipitation, and positively with the hours of sunshine during grain-filling. In contrast, of the air temperatures tested, the gelatinization temperature of the rice grains (63.2°C to 70.0 °C) correlated positively and most strongly with the mean daily mean air temperature. Thus, we identified the mean daily minimum temperature during grain-filling, a nocturnal temperature, as a major factor affecting the isotopic and thermal variations in rice grains.

中文翻译：

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碳和氧稳定同位素组成和水稻糊化温度对气候变化的长期响应。

稻米中碳（δ13C）和氧（δ18O）的稳定同位素组成通常用于证实其真实性。糊化温度是酒精发酵的关键因素。但是，关于水稻对气候变化的同位素和热响应知之甚少。我们发现，在1994年至2013年同一稻田中每年种植的缘故稻中，δ13C（-27.4‰至-25.9‰）和δ18O值（20.4‰至27.0‰）与日平均最低气温和降水量呈负相关，并与谷物填充过程中的日照时间成正比。相反，在测试的空气温度中，米粒的糊化温度（63.2°C至70.0°C）与平均每日平均气温呈正相关，且最强。因此，我们确定了灌浆过程中的每日平均最低温度，