Influence of Variety and Crop Year on Lipid Content and Fatty Acid Composition of Lowland Non-Glutinus Brown Rice

The influence of variety and crop year on lipid content and fatty acid composition of brown rice was investigated on the 24 lowland non-glutinous varieties cultivated at Hiroshima Agricultural Experiment Station in 1976 and 1977. Lipid content and stearic acid, oleic acid, and linoleic acid contents were significantly affected by variety and crop year and palmitoleic acid and linolenic acid contents were significantly affected by crop year. As to the fatty acid composition in 1976 and both the years (1976+1977), the daily mean temperature during ripening showed significantly positive correlations with palmitoleic acid, stearic acid, oleic acid, and arachidic acid contents and negative correlations with myristic acid, palmitic acid, lino-leic acid, and linolenic acid contents. On the other hand, no significant correlation between daily mean temperature during ripening and fatty acid content was observed in 1977. With respect to the reason, it was presumed that there was no marked difference in the temperature among the varieties in 1977 because of higher temperature from the middle of August to the middle of September as compared with 1976. Oleic acid content showed significantly negative correlations with linoleic acid and linolenic acid contents and linoleic acid content showed significantly positive correlation with linolenic acid content in 1976, 1977, and both the years. The relation between oleic acid content (X%) and linoleic acid content (Y%) was expressed by the following regression equation from the values of both the years. Y=-0.759X+68.21.