Abstract
To test the applicability of the temperature gradient chamber (TGC) method to the evaluation of the high temperature ripening ability of rice, five varieties of rice were cultivated in TGC environments. The temperature gradient occurred in the TGC as expected, and experiments under different conditions of gradual temperatures became possible. As an index of the high temperature ripening ability, the relationship between the milky white kernel ratio, basal white kernel ratio, white back kernel ratio and the average temperature during the ripening stage was investigated. As a result, it became evident that the frequency of the types of white immature kernels differed from variety to variety, such as milky white kernel of “Hitomebore” and basal white kernel and white back kernel of “Niigatawase”. These results indicated that the TGC could be applied to evaluate the high temperature ripening ability of rice. The implications of the subsidiary findings indicating that the occurrences of white immature kernels depended on the rice varieties, and also the ripening stage of the exposure to high temperature were examined.
