Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/7/2005
Publication Date: 8/26/2005
Citation: Lozovaya, V.V., Lygin, A.V., Ulanov, A.V., Nelson, R.L., Widholm, J.M. 2005. Effect of temperature and moisture status during seed development on soybean seed isoflavone concentration and composition. Crop Science. 45:1934-1940. Interpretive Summary: Soybean seed isoflavones have been shown to have beneficial effects on human health so interest in soy foods in the diet has been increasing in the U.S. and other parts of the world. It is known the environmental conditions can substantially change isoflavone concentrations in soybean seeds, but specific effects of air temperature and soil moisture content are unknown. Our results demonstrated that lower temperatures and moist soil conditions produced the highest isoflavone concentrations. There were significant differences among varieties for response to variation in soil moisture but all varieties tested showed a 2 to 3-fold increase in total isoflavone concentrations as the temperature was lowered from the highest to the lowest temperatures tested. We also found large differences among the varieties tested in all of the temperature and soil moisture treatments demonstrating the strong genetic control of isoflavone concentration. These results will be of interest to those seeking to exploit environmental conditions to alter isoflavone concentration and to breeders and geneticists who are interested in understanding the genetic control of soybean seed isoflavones.
Technical Abstract: To determine the effect of temperature and water status during soybean seed development on seed isoflavone concentration and composition, soybean plants were grown in the greenhouse under optimal (18/28%), sub-optimal (13/23°C) or super-optimal (23/33°C) 9.5 hour night/14.5 hour daytime temperatures with either optimal or sub-optimal water conditions. Two French cvs., Imari and Queen, and three U.S. cvs., Dwight, Jack and Loda, all of maturity group II were studied. The overall results show that sub-optimal temperatures and optimal soil moisture conditions produced the highest seed yield and seed isoflavone concentrations. The concentrations of daidzein and genistein followed the overall isoflavone concentration changes while the glycitein concentration was much less affected. The three U.S. cvs. were much less responsive to soil moisture than the three French cvs. However, all five cvs. showed a 2 to 3-fold increase in total isoflavone concentrations as the temperature was lowered from super-optimal to sub-optimal. Thus the environmental factors, soil moisture status and temperature, have clear effects on the isoflavone concentrations in soybean mature seeds, but the ranking of all the cvs. by average isoflavone concentration remained the same. This indicates that while environmental factors have a large effect on isoflavone concentration, the potential for isoflavone production also has a very strong genetic component.