Abstract
In this paper the coefficients of correlation between the yield of potatoes and the weather factors (monthly mean temperature, monthly amount of rainfall and monthly total hours of sunshine in the cultivating period) have been calculated by the method previously reported in this magazine, for each prefecture of Japan. The correlation coefficients calculated are given in tables 1, 2, and 3. Indeed these values do not show sufficiently the relation between the yield of potatoes and the weather factors, but there are recognized the following facts.
1. In the Tõhoku and Hokkaidõ districts it is favourable for the yield of potatoes when the weather is warm at the early stage of growth, and warm, rainless and sunny at the tuber-setting time.
2. In the other districts than above-mentioned the relation is not similar for the prefectures.
