CLASSIFICATION OF RICE CULTIVARS FOR SAKE BREWERY BASED ON WHITE-CORECHARACTERS

One of the important factors in the use of rice for sake brewery is re presented by the characters of the white-core in kernels. Rice breeder s and sake brewers require information about the size and position of the white-core in grains of rice cultivars for sake brewery. However, it had hitherto been difficult to obtain the information, because the size and position of the white-core in grains vary with the cultivars. We reported that the evaluation of the size and position of the white -core is possible by using image analysis, in which the standard image for a cultivar was obtained by superimposing the image of 85 grains ( 1996). In this study, we aimed at detecting the difference in the whit e-core characters in grains among rice cultivars for sake brewery by u sing the standard images. It was reported that the size of the white-c ore correlated with the thickness of the rice kernel. Then we classifi ed the grains into 5 groups according to their thickness and made the standard image of each group. The results showed that the size of whit e-core correlated with kernel thickness, i. e. the thicker the grain, the greater the size of the white-core. On the other hand, the positio ns of the white-core in grains did not differ among the 5 groups (Fig. 2, 3). Therefore, the standard images of 34 cultivars were obtained, using grains more than 2.0 mm thick from rice plants cultivated in Nag aoka city, Niigata prefecture in 1995. Based on the comparison of the 34 standard images, we classified the cultivars into 5 categories (Fig . 4). Then we reviewed the genealogical tree of the rice cultivars for sake brewery based on the literature, and investigated the relationsh ip between the lineage and the characters of the white-cores. It was f ound that the cultivars which were closely related gave a similar stan dard image (Fig. 5). These findings support the assumption that charac ters of the white-core are genetically controlled. The results obtaine d suggest that the method of evaluation applied is not valid for the s election of raw materials for sake brewery, but also could be used as an index of breeding.