2026 Volume 95 Issue 1 Pages 48-53
The cracked rice kernel is a phenomenon in which cracks appear in the endosperm of brown rice. and when they occur frequently, they have a significant impact on the quality of agricultural products, including a decrease in inspection grade and eating quality. This phenomenon has been observed in many areas in recent years, and although countermeasures are urgently needed, the causes of the cracking have not been fully elucidated. Therefore, this study aimed to investigate the occurrence of cracked grains under various weather conditions by setting multiple cropping seasons and to clarify the weather factors associated with cracking. The relationship between post-heading temperature and cracking was examined by comparing the average of daily maximum temperature during 15 days after heading and the percentages of slightly-cracked grains at the accumulated temperature of 800ºC・d and 900ºC・d after heading. The results suggested that high post-heading temperatures cause slightly-cracked grains to appear before full ripening. Heavily-cracked grains tended to occur more frequently when rice moisture content was less than 22%. At a moisture content of 22% or less, there was a high correlation between the percentage of total and heavily cracked grains and maximum daily transpiration forcing (FTP); cracked grains tended to occur more frequently when maximum FTP exceeded 40.
