Decreasing radioactive cesium in lodged buckwheat grain after harvest

This study assessed soil contamination with high radioactive cesium (R-Cs) concentration in buckwheat grains by lodging, and assessed the possibility of R-Cs reduction in grain through post-harvest preparation. Analysis of buckwheat grain produced in farmers' fields and reports from farmers indicated that grain from fields that had lodging showed higher R-Cs than grain from fields with no lodging. A field experiment demonstrated that R-Cs in grain after threshing and winnowing (TW) was about six times higher in lodged plants than in nonlodged plants. In lodged plants, R-Cs in grain was decreased to about one-fourth by polishing, and was decreased to about one-seventh by ultrasonic cleaning, compared with R-Cs in grain after TW. These results demonstrate that R-Cs of buckwheat grain of lodged plants can be decreased by removing soil from the grain surface by polishing and winnowing.