北海道でも最も冷涼な稲作地帯で生産されるもち米の外観品質を，栽培6地域で4カ年調査した。年次間では，障害型冷害危険期の平均気温と出穂後40日間の日平均積算気温（登熟気温）が高いほど，不稔歩合が低く千粒重が重く多収で，整粒歩合が高く未熟粒，被害粒および着色粒歩合が低くなり，精米蛋白質含有率が低く玄米白度と精米白度が高かった。一方，地域間でこれらの関係が概して不明確だったが，これは生育期別気温，生育特性および整粒，未熟粒歩合における変動（最小値最大値の差異および変動係数）が地域間よりも年次間で大きいためだった。ただし，被害粒と着色粒歩合は，変動が地域間よりも年次間で小さく，年次と地域込みで登熟気温が各845，857 ℃で最低となる2次回帰の関係を示した。また，整粒歩合では年次間と地域間で，被害粒と着色粒歩合では年次間のみで，それらが不良なほど年次では地域間，地域では年次間の変動係数が大きかった。なお，乾燥後も半透明な未ハゼ粒は，白濁不透明なハゼ粒との間に蛋白質含有率，澱粉含有率，澱粉粒の大きさ，精製澱粉でのヨウ素吸収曲線の最大吸収波長とその吸光度の理化学的特性および餅生地明度で差がほぼ無く，餅生地の物理特性でも大きな差異が無いため，未ハゼ粒のもち米への混入は餅生地加工で問題とはならないと考えられた。また，粳花粉との交雑により糯品種の胚乳が粳性となるキセニア粒は，不稔が多いと多発生し，粳と糯品種の圃場間の隔離距離が長いほど減少するが，距離600 mでも発生した。北海道では品質低下を避けるため糯品種を粳品種圃場から離れた地域で栽培している。
Appearance quality of glutinous rice grains produced in the six areas of cultivation in the coldest regions for rice cultivation in Hokkaido, Japan was investigated during four years. Among years, the higher the temperature during the stage sensitive to sterile-type cool injury, and the cumulative daily mean temperature during 40 days after heading (grain-filling temperature), the lower the sterility, the heavier the 1000-kernel-weight, the higher the grain yield, higher the percentage of whole grain, the lower the percentages of immature, damaged and colored grains, the lower was the protein content, and the higher was the whiteness of both brown rice and milled rice. On the other hand, the relationship among the 6 areas was not clear. This was because the range of the yearly variation (differences between the two extreme values and coefficients of variation) in the temperatures during the growth stages, the growth characteristics, and the percentages of both whole grain and immature grain were larger than the regional variations. However, the range of the yearly variation in the percentages of damaged grain and colored grain were smaller than the regional variations, and the percentages of damaged grain and colored grain were the lowest in the quadratic regression relationship, at the grain-filling temperature of 843℃and 857℃, respectively, among the 6 areas during the 4 years. In addition, the percentage of whole kernels varies between years and regions, and the affected kernels and colored kernels only change between years; the worse these characteristics, the the larger the coefficient of variation among years in the same area or among areas in the same year. Moreover, glutinous grains, called mihaze grains, that are translucent after drying, did not show clear differences in physicochemical characteristics such as contents of both protein and starch, size of starch granules, iodine absorption spectrum of prepared starch and lightness of rice-cake dough as compared with the opaque grains called haze, and did not show large differences in physical property of rice-cake dough. Therefore, contamination of mihaze grains is considered to have little effect on the processing quality of rice-cake dough. Xenia seeds of glutinous rice plants occurred by outcrossing with pollen of a non-glutinous variety, and were found more in rice plants with high sterility than those with low sterility. The longer the isolation distance from non-glutinous variety to glutinous rice plant; the lower was the Xenia seed rate. However, Xenia seeds were found even at an isolation distance of 600 m. Therefore, in Hokkaido, to avoid quality deterioration, glutinous rice varieties should be cultivated in a district distant apart from paddy fields of non-glutinous rice varieties.