Effect of temperature during the seed-filling period and varietal differences in soybean isoflavone content and components in cold districts

Abstract

The isoflavone content of soybeans cultivated in Hokkaido was investigated, in terms of varietal and local differences. There was a significant negative correlation between isoflavone content and temperature during the seed-filling period, in each cultivar cultivated in various experimental locations in Hokkaido. "Yukipirika" had the highest isoflavone content, followed by "Otofuke-Osode". "Yukipirika" had a 1 . 3-1 . 5-fold higher isoflavone content than the standard cultivar in any experimental location, and had lower coefficients of variation among locations and years. In "Yukipirika", the accumulation of daidzin (and its relatives) was especially high, and the ratio of daidzin to genistin (D / DG ratio) was high. However, the isoflavone content and D / DG ratio did not significantly vary with the cultivar and progeny. On the other hand, the D / DG ratio in the same cultivar cultivated in various locations negatively correlated with the temperature during their seed-filling period, suggesting that the conditions that accelerate the isoflavone accumulation would also affect the D / DG ratio.