全球变暖对日本寒地北海道2030年代水稻生育的影响预测及其对策

Prediction of the Influence of Global Warming on Rice Growth in the 2030s in Hokkaido,the Coldest Region in Japan and the Measures to Be Taken for Sustained Production

北海道从1980年代开始到2010年代为止,水稻大田栽培期间的5–9月份气温随着年代而不断上升。与最近的2010年代(2010—2019年平均)相比,使用两种2030年代的预测气象,根据以往研究得到的关系方程预测研究了水稻生育。其结果,2030年代比2010年代,插秧日期期限(插秧最早期限)比水稻栽培17个地区平均值要早8~9天。另外,抽穗日期最早期限要早1~5天,抽穗日期最晚期限要晚1~5天,安全抽穗期间要长2~10天,抽穗日期要早1~3天。由于从抽穗日期到最晚抽穗为止要长2~9天,延迟型冷害的发生要略少。关于各生育期的气象,抽穗前24天以后的30天期间的平均气温因为生育早而相同或略低。抽穗前10天以后的40天期间以及抽穗日期以后的40天期间的平均气温略高,日射量略少。因此,糙米产量为96%~98%,要略低,显示潜在产量特性的气候灌浆量指数相同。因为与障碍秕粒发生有关的孕穗期冷害危险期的平均气温略低或基本相同,带来发生冷害的风险。另一方面,引起秕粒发生的低温区的出现频率在地区间具有差异。虽然大米蛋白质含量相同,但直链淀粉含量略低、食味略良。关于米粒外观品质,受害粒比率和着色粒比率没有一定的变化趋势,未熟粒比率略高,大米白度相同,糙米白度略高。通过上述预测研究显示了未来日本寒冷地带水稻生育的技术应对方向。

The mean air temperature from May to September,during which the rice plant is cultured in the paddy field in Hokkaido,has increased during the four decades from 1980 to 2019.The growth of rice in the 2030s in comparison to the most recent decade(2010—2019)was predicted using two predicted weathers for the 2030s and the previously reported relational expression.In the 2030s,the critical planting date(early limit of planting day)will be 8~9 days earlier than that in the 2010s.The early limit of heading date will also be 1~5 days earlier,and the late limit of heading date will be 1~5 days later.Therefore,the safe heading period will be 2~10 days longer and the heading date will be 1~3 days earlier.As the period between heading date and late limit of heading will be 2~9 days longer,cool summer damage due to delayed growth will decrease slightly.Concerning the weather at different growth stages,the average air temperature will be the same or lower for the earlier growth during the 30 days after 24 days before heading.During the 40 days after 10 days before heading and during the 40 days after heading,the average air temperature will be slightly higher,and the amount of solar radiation will be slightly lower.Then the grain yield will be slightly lower(96%~98%),and the agroclimatic index for expressing the potential of grain yield will be the same.As the average air temperature during the critical stage of chilling injury at the booting stage,which is related with occurrence of male sterility,will be slightly lower or the same,the risk of occurrence of cool weather damage will remain.On the other hand,the appearance frequency of low temperature,which causes sterility,will vary depending on the area.The protein content of milled rice will be the same and the amylose content will be slightly lower.Therefore,the palatability will be slightly better.On the appearance quality of rice grain,there will be no consistent tendency between the 2030s and the 2010s in the percentages of damaged grain and of colored grain,and the percentage of immature grain will be slightly higher.Although the whiteness of milled rice will be the same,the whiteness of brown rice will be slightly higher.The measures to be taken in response to the above predictions are discussed,for rice growth in the future in the coldest region,Japan.