Climatic Change and Rice Yield and Production in Japan during the Last 100 Years

Abstract

First, general trends of rice yield and production and changes of air temperature, precipitation and sunshine hours in Japan during the last 100 years are described. In yield, three periods can generally be recognized: Period 1, from the end of the 19th century to about 1915, Period 2, from about 1915 to about 1945, the end or just few years after the 2 nd World War, and Period 3, after the end of the 2 nd World War. Secondly, fluctuation of climatic conditions and its effects on the paddy rice yield during the last 104 years were studied statistically in order to evaluate the different impacts according to period. By applying the principal component analysis method, their distributions, periodicities and relations to monthly mean air temperature, monthly total precipitation, and monthly total sunshine hours were studied. The first component has a significant correlation to all three climatic elements in July, and air temperature and sunshine hours in August and precipitation and sunshine hours in September.
In the second part of this study, we classify the 104 years into three periods according to interannual changes of paddy rice yield. For these three periods, the general trends and fluctuations are described and the relationship between the yield and climatic elements are analyzed for five regions respectively.