Abstract
The temperature of the filling of soybean seeds had a drastic influence on the isoflavone content in the seeds. The content of isoflavone was the highest at 20℃, followed by 25℃, and the lowest at 30℃. Moreover, the 100 grains weight of soybeans grown at 20℃ and 25℃ was large in comparison with that of the soybeans grown at 30℃. From the above, a temperature of 20℃ was concluded to be the environment to increase most greatly the isoflavone content in soybean seeds among these conditions. In all the soybean cultivars used in this experiment, the main isoflavones accumulated in soybean seeds were malonyldaidzin and malonylgenistin, and the content of glucosides and malonylglucosides increased with the filling of the seeds. Therefore, it became clear that the main storage form of isoflavone in the soybean seeds was malonylglucosides. In the soybean cultivation of Fukuoka Prefecture, the present seeding period is mid-to late-July, and the maturity period is early-to mid-November. To increase the content of isoflavone in seeds, the seeding period must be reexamined to keep the temperature of the maturity period at less than 20℃. For that achievement, it is necessary to delay the seeding period from early-to mid-August so that the maturity period may be late-November. As a result of that, it is estimated that the isoflavone synthesis ability of soybean seed will be brought out to the full and that the soybean seeds with a high content of isoflavone can be produced.
