Abstract:Glutinous rice is produced in the coldest and the severest regions for rice cultivation in Hokkaido, Japan. The rice quality of four years and six cultivation areas with large fluctuation in yield and quality was investigated.. Among years, the higher the temperature during the stage sensitive to sterile-type cool injury, the lower the sterility. Moreover, the higher the cumulative daily mean temperature during 40 days after heading (grain-filling temperature), the heavier the 1 000-kernel-weight, the higher the grain yield, the lower was the protein content and the higher were the whiteness of both brown and milled rice. However, the correlation among different planting areas was not clear. This was because, compared to the range of the regional variation (differences between the two extreme values and coefficients of variation), the range of the yearly variation in protein content was 1.0 and 1.3 times larger, the mean temperatures during some growth stages and growth characteristics like grain yield were 1.3~8.5 times higher, and the whiteness of both brown and milled rice were 1.6~2.6 times larger. It should be noted that the protein content was the lowest in the quadratic regression relationship at a grain-filling temperature of 849 ℃, among the 6 areas during the 4 years. In addition, concerning the mean values for year and area, the lower the temperature during the sensitive stage to sterile-type cool injury, the higher the sterility, the lighter the 1 000-kernel-weight, the lower the grain yield, the higher the protein content, the lower the whiteness of both brown and milled rice; namely, the worse these characteristics, the larger the coefficient of variation among areas and years. Moreover, the whiteness of both brown and milled rice showed positive relationships with grain-filling temperature per one unhulled rice in one square meter. Therefore, the number of unhulled rice in one square meter could be calculated from the grain-filling temperature per one unhulled rice to reach the target value of whiteness of brown rice and the grain-filling temperature in a normal year in the target area, and then the amount of nitrogen fertilizer application to obtain the target value of whiteness of brown rice could be determined.