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

利用cv对糙米的食味性状与厚度、重量的关系进行了评价。产自茨城县的光果，其成熟温度在不同的栽培地区有所不同。结果表明，糙米大小与食味性状的关系随栽培年限和栽培条件的变化而波动。然而，晶粒厚度对这些关系的影响大于粒重。另一方面，综述了世界和（或）日本水稻生产和种植面积的变化。通过扫描电镜观察，表征了高、低美味米饭的典型特征。此外，还阐明了裂粒的超微结构、淀粉体的异常增生和糯粒的垩白结构。

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.