Relation between the Yield of Sweet Potatoes and the Weather Factors. Part I

[摘要] The coefficients of correlation between the yield of sweet potatoes and the weather factors (monthly mean temperature, monthly amount of rainfall and monthly total hours of sunshine) have been calculated by the method previously reported in this journal, for each prefecture in Japan and for each month from May to November. The correlation coefficients calculated are shown in tables 1, 2 and 3, and althouhg they do not indicate well the influence of the weather factors on the yield of sweet potatoes. the following results are found from them at least.1. The correlation of the yield with the temperatures in early time of growht and in harvest time is positive for every prefecture. and that of the yield with the temperature from July to August is generally negative for the other districts than the northeastern. The former correlation may be explained by the fact that the sweet potato is a crop of subtropical origin, while the latter correlation is explained by the other fact that high temperature, accompanied by sunny weather, often brings dorought injuries, especially in hte southerm part of Japan.2. The correlation of the yield with the rainfall is almost positive in the southern district and negative in the nortern.That the local difference in the correlation of the yield with the rainfall is remarkable, is considered to be due to the local difference in soil nature.3. The correlatian of the yield with the sunshine is similar to that with the temperature. This is because the sunny weather is liable to accompany high temperature.

[学科分类] 大气科学