Relation between the Yield of Aquatic Rice-crop and the Weather Factors. Part I

[摘要] In this paper the coefficients of correlation between the yield of aquatic ricecrop and the weather factors (monthly mean of air temperature, monthly amount of rainfall, and monthly total hours of sunshine) during the period from 1902 to 1937 were computed by the following formula for each prefecture in Japan, each from April to October: where DY represents departure of the yield of ricecrop from the moving mean by the 5 years, and DW that of the weather factors.The correlation coefficients of the temperature and of the sunshine with the yield are almost positive, while that of the rainfall is mostly negative as shown in Tables 1, 2, 3.From the above results we see undoubtedly that warm, dry and sunny weather in Japan is favourable for rice-crop. Relations between the yield and the weather factors in the northern districts of Japan are slightly different from those in the southern districts.In the northern districts the correlations between the yield and the weather factors are generally highest during the ear-appearing period. This indicates that the summer air temperature in the northern districts has direct influence upon the yield of rice-crop as a limiting factor.In the southern districts, the correlations between the yield and the weather factors are lower than in the northern districts and the yield of rice-crop is largely dependent on the temperature during the transplanting period and on the sunshine during the period from flowering to fruiting, and then the rainfall has not so much influence as we have expected.

[学科分类] 大气科学