Abstract
After the heavy damage of cool summer in 1953, rice yield in Tohoku has been steadily increasing. However it dropped in 1976 to 90 in rice crop condition index suffering cool summer damage, i. e. low temperature, much rainfall and poor sunshine during August and September. The author believes that postwar change in rice cultivation aggravated the situation.
To clarify the reason of the great damage in rice crop the author investigated the area of postwar paddy field newly reclaimed.
The distribution of heavy damage roughly correspondes to rice cultivation land reclaimed during 1960's. Especially it was the most severe in Iwate prefecture. Topographical analysis indicates the correlation between altitude and damage as expected naturally.
However, detailed investigation at GOKURAKUNO settlement on the southern foot of Mt. Iwate as a typical example, revealed not only a simple correlation with altitude or low temperature, but also with the failure in adoption of proper cultivation techniques, especially in the use of cold registance rice variety and provision for raising water temperature. The rice cultivation on reclaimed land gave rise to recurrence of cool summer damage.
It looks to reflect problems inherent in postwar agriculture development of Japan: uneven distribution of regional prosperity and Tohoku's position depending on rice cultivation.
