Trends and annual fluctuations in selenium concentrations in wheat grain

Selenium concentrations were determined in grain from four varieties of winter and spring wheat grown in the same area during 1918–1979 and 1930–1980, respectively. Concentrations in the four longest series tended to decrease over time. The annual variation, expressed as the coefficient of variation, ranged between 51%–62% for the four investigated series. According to regression calculations, an additional 100 mm of precipitation during the growing season (May-August) would lead to a 7.2 ng Se g−1 increase in the Se concentration of spring wheat grain. For winter wheat grain the calculated increase was not significant. No correlation was found between grain yield and grain Se concentration. Although there was a significant difference in grain Se concentrations between spring wheat varieties. there was no indication that older varieties differed from newer ones in this regard.