Anthocyanin Content, Isoflavone Composition, Antioxidant Activities, and Agronomic Performance of Black Soybean Lines

Abstract

Modern soybean cultivars are expected to combine good agronomic performance and enhanced bioactive properties. This study aimed to evaluate the anthocyanin content, isoflavone composition, and antioxidant activities of black soybean genotypes associated with agronomic performances. Sixteen black soybean genotypes were evaluated in a field experiment arranged in a randomized block design with four replicates. The total anthocyanin content (TAC), antioxidant activity, and isoflavone composition (daidzein, glycitein, and genistein) were quantified in the seed coat and cotyledon. The results showed that the TAC, antioxidant activity, and isoflavone composition varied among the 16 genotypes. TAC was higher in the seed coat (283.6906 mg/100 seed) than in the seed cotyledon (118.2556 mg/100 g). Genotypes with high TAC in the seed coat had a black seed coat, while those with high TAC in the cotyledon had a green color. The concentration ranges of daidzein, glycitein, and genistein were 9.42-27.94 mg/kg, 25.18-67.14 mg/kg, and 12.93-34.52 mg/kg, respectively. Antioxidant activity in the seed cotyledon was generally low but ranged from low to strong in the seed coat. Three genotypes exhibited strong antioxidant activity in the seed coat. The number of nodes was identified as a useful selection criterion for high-yielding genotypes. The Genotype-by-Trait (GT) biplot showed that the genotype G2 (JPG 15/Anj-884) had the highest values for all isoflavone compositions. Genotypes G6 (Khl/Anj-890), G7 (Khl/Anj-891), and G8 (Khl/Anj-893) performed best in terms of seed yield and antioxidant activity both in the seed and cotyledon. Genotypes G9 (Khl/Anj-894), G11 (Khl/Anj-896), and G15 (Mallika) had large seed size and high TAC in both seed and cotyledon. These genotypes have potential for further improvement, either as promising lines or parental lines in developing new black soybean cultivars.