우리나라 水稻作의 豊凶과 氣象環境과의 關聯性에 關한 硏究 : The Variability of Rice Yield and Its Dependence on Weather in Korea

다국어 초록 (Multilingual Abstract)

An analysis was made of annual rice yield trend, variability and its dependence on weather condition in Korea since 1925.
The results obtained are summarized as follows;
1. The time series of rice yield was best fitted to two segmented-linear regression lines whose inflection point was set in 1964. the rice yield recorded very dull increase of 2.4kg/10a/ year before 1964, but thereafter sharp increase of 12.4kg/10a/year. Through 1925 to 1980 Gangweon showed the lowest increasing rate and Chungnam the the highest.
2. The annual variability of rice yield tended to decrease with time up to the ealier part of 1970's, but thereafter again to increase. Among provinces Gangweon showed the lowest yield variability (C.V.=10%) and Gyungbuk the greatest (C.V.=15.3%).
3. During 1927 to 1980, two years, 1939 (drought) and 1980 (summer cool), were recorded as the worst harvest years (1-YI>??) and six years, that were entirely distributed before 1962, as worse years (??<1-YI<??). The causal factors to the worse harvest years consists of four times of synchronous damage by drought and flood, and of two times of synchronous damage by drought and autumnal cool. Since 1960's, drought had occurred five times and flood three times, but all those years except 1962 and 1980 were recorded as normal or good harvest years, suggesting that the drought and flood disasters have been overcome somewhat due to the improved production environments.
4. The correlogram of yield index (YI) showed periodical fluctuation with short periodicity, suggesting that the time series of yield index include a certain periodicity.
5. The power spectral analysis showed that the yield index time series fluctuate with periodicity of 3.5 years (0.285 cycles/year) with highest peak of power density. This periodicity of 3.5 years seems to correspond to the climatic disater due to bad weather conditions at an interval of 3 to 4 years.
6. Among weather factors, average hours of sunshine in August and average temperature in July, August and September seem to exert great effects on the annual yield variability.
7. The inter-provincial differences in the annual rice yield variability tended to be closely associated with the annual variability (standard deviation) of average temperature during July to August (??). And the standard deviation of temperature tends to be greater in the region with higher average temperature (??).