Since publishing a short article on this subject in 1932, the writer has been studying certain districts in Hokkaido with respcet to rice cultivation. A summary of his second article follows.
(1) One of the climatic elements that influences the rice crop in Hokkaido is the temperature during the growing season, especially in the month of August, precipitation has no influence on it (see Table 1 ).
Table 1 Correlation coefficients, both of the rice crop and the climatic elements in Hokkaido.
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Note - Δ figures for Akita Prefecture (Northern Japan) by Eiitirô Hukui.
This is one of the characteristic of rice culture in Northeastern Japan, where they have special devices for watering the rice field. From the fact that the regional development of rice cultivation (Fig. 4) resembles the August temperature map (Fig. 5), the author believes that the rice crop is absolutely dependent upon the latter.
(2) Rice cultivation has spread northeastwards under the direct influence both of climate (summer temperature) and the general rise in the price of rice; this will be seen from Table a. The present limit of rice cultivation in Hokkaido is the temperature belt of 19-19.5°C., namely, August tempera-ture, its growing season lasting about 110-130 days.
Table 2 The regional development of rice cultivation in Hokkaido.
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(3) The Rice Cultivating Provinces (Figs. 6-12 )
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(4) The regional spread of rice cultivation accompanies success with seedbreeding; a new kind of seed that requires only 100 days for its development having been raised. It will soon be possible to raise commercial rice crops in the boundary provinces. Rice culture in Hokkaido presents many very interesting aspects. The Japanese being a rice-eating race, have as the result of careful and protracted studies of the climate and soil conditions, overcome the handicaps of nature by developing a new breed of rice suited to the climate.

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