Inheritance of qualitative traits and heterosis in bambara groundnut (Vigna subterranea (L.) Verdc.)

Genetic inheritance studies and varietal improvement programs in bambara groundnut have not been initiated in the past due to failure in hybridization. We successfully produced 23 F, seeds from four crosses among the morphologically distinct lines, "TVsu 11," TVsu 870," "TVsu 1061," and a Thai local variety "Thung Yang Daeng." The phenotypes of the F, showed that the reddish-purple pod and red seed coat were dominant over the white pod and cream seed coat. The F-2 from the cross between a reddish-purple pod line and a white pod line, and between a red seed coat line with a cream seed coat line segregated in a 3:1 ratio. This simple Mendelian inheritance was confirmed by the segregation ratio in the F-3 generation. In terms of petiole color, reddish-purple was dominant over green. However, the segregation in the F2 generation revealed that this trait was controlled by more than one gene locus. For leaflet shape, incomplete dominance was found in the F2 population of the cross between "Thung Yang Daeng," with a long narrow leaflet, and "TVsu 870," with a lanceolate leaflet, giving a 1:2:1 segregation ratio among long narrow:moderately long:lanceolate leaflets. Significant hybrid vigor of the F-1, as determined from heterosis and heterobeltiosis, was found in petiole length, fresh pericarp thickness, and seed size.