Changes in lutein and tocopherol concentrations in soybean cultivars released across seven decades in the short-season region

Lutein and α-tocopherol (α-toc) are antioxidant compounds beneficial for human health. Soybean [Glycine max (L). Merr.] contains relatively high concentrations of these compounds, and increasing them through plant breeding may be beneficial to human nutrition as well as provide a marketable seed trait in food-type soybean. Our objective was to determine if there have been changes in lutein and tocopherol concentrations in short-season soybean cultivars. A historical series of 16 cultivars released from 1934 to 2000 were grown at Ottawa Canada over a 3 yr period in a randomized complete-block design with four replications. Seed was harvested for yield and a sample taken to determine seed weight, and oil, protein, lutein, α-toc, γ-tocopherol (γ-toc), δ-tocopherol (δ-toc), and total-tocopherol concentrations. There were significant differences among cultivars for all traits examined. Seed yield, oil, lutein, α-toc, and δ-toc concentrations have increased significantly since 1934, while protein concentration has decreased. There were no changes in seed weight and γ-toc over time. Lutein and α-toc were positively correlated with oil concentration and negatively correlated with protein concentration, leading to the conclusion that, over time, these compounds have likely increased in short-season cultivars due to the indirect selection for higher oil concentration by plant breeders. The maximum concentration of lutein and α-toc were similar to those found in other studies from different soybean growing regions indicating that only modest increases in these compounds may be possible using standard breeding techniques.