| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
Rice (Oryza sativa L) has been one of the most important crops for the world's inhabitants especially in Asian countries. While the pericarp or testa of wild-genotype rice is either red or black in color, white rice has been favored and selected during the past centuries presumably because of its appearance and good taste as well as the high production efficiency. In Japan, colored rice, especially red, has been maintained in limited areas such as in Sonja (Okayama Prefecture), Tsushima Island (Nagasaki Prefecture), and Tanegashima Island (Kagaoshima Prefecture) for religious purposes as an offering to natural God Shinto shrines. Black rice has been cultivated in some Asian countries including China and Indonesia for religious purpose or as traditional food.
Since approximately 10 years ago, wild-genotype rice has become popular as "ancient rice" among natural food lovers in Japan because they are stronger than white rice against pathologic insects and weeds, thus requiring less insecti
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cides, herbicides, and chemical fertilizer. Furthermore, natural pigments in plant attracted much attention because of its possible antioxidant activity hi human body based on a hypothesis that endogenous antioxidants play an important role in plant defense system against oxidative stress.
We have investigated the variability of mineral contents and that of the antioxidant activities in different strains of colored rice in order to determine the relation between mineral content and antioxidant activity, as well as their relationships to kernel characteristics. Information about these relationships should prove valuable for functional evaluation of colored rice and, should provide a basis for making genetic improvements in colored rice.
The Fe content of the kernel varied from 3.79 to 17.95ppm, the average being 10.14ppm and the coefficients of variation of 23.9%. The highest value for Fe content was for HAJIKUROHO from a red rice strain that had a relatively low kernel weight of 1.634g and a waxy rice starch. The lowest value was for TAKASAGOMOCHI from a white rice strain that had a relatively high kernel weight of 2.210g and a waxy rice starch. The Ca content of the kernel ranged from 77.92 to 160.66, averaging 110.63ppm ; whereas, the Zn content ranged from 10.78 to 27.36ppm, averaging 16.82ppm. The respective coefficients of variation for Ca and Zn were 12.9% and 18.7%. The highest Ca value was for RYOUYOU-KUROMAI from a black rice strain having long kernel length of 6.83mm. The lowest value was for YAMABIKO from a black-seeded strain having short kernel length of 5.46mm. The highest and the lowest values, respectively, for Zn were found in samples from the red rice strain. No strains were found to have a markedly high mineral content, which would increase the quality of both the nutritive value and oxidative stress. We fund a valid association between seed color type and the Ca content of the kernel. Strains that had black-colored rice tended to have higher Ca contents. We found valid strains to have a relatively high antioxidant activity, which were for ASAMURASAKI from a black rice strain and TUKUSI-AKAMOCHI from a red rice strain. Less
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