Morphological analysis on the decrease of thickness, weight and quality in rice grain under high/low ripening temperature

利用cv。产自茨木县的越光，成熟温度因栽培地区而异。结果表明，糙米粒大小与食味性状的关系随栽培年限和栽培条件的不同而波动。然而，对这些关系的有效性较大的粒厚，而不是粒重。另一方面，综述了世界和日本水稻生产和种植面积的变化。通过扫描电镜观察，对高、低适口性米饭的典型特征进行了表征。此外，还阐明了稻米裂粒的超微结构、造粉体的异常增殖和糯性稻米的垩白结构。

Evaluation was conducted on relations between palatable characters and thickness and weight of brown rice using cv. Koshihikari produced in Ibaraki prefecture of whose ripening temperature is different among cultivation areas. As a result, relations between the size of brown rice and palatable characters were fluctuated by cultivation years and conditions. However, the effectiveness on these relations were larger by grain thickness rather than by grain weight. On the other hand, the changes of rice production and cultivation area in the world and/ or Japan were overviewed. Typical feature of high or low palatable cooked rice were also characterized by scanning electron microscopic observations. Moreover, ultra-fine structures of cracked rice grain, abnormal proliferation of amyloplasts, and chalky structure of waxy rice grain were clarified.