In vitro plantlets regeneration in Bambara groundnut [Vigna subterranea (L.) Verdc. (Fabaceae)] through direct shoot bud differentiation on hypocotyl and epicotyl cuttings

In vitro regeneration system via direct organogenesis in Bambara groundnut (Vigna subterranea L.) using hypocotyl and epicotyl cuttings was studied. Basal Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP), 6-furfurylaminopurine (kinetin) or Thidiazuron (TDZ) with or without
-naphthaleneacetic acid (NAA) were attempted. Multiple shoots were induced from both explants but regeneration efficiency was higher when epicotyl cuttings were used. The ability of hypocotyl and epicotyl cuttings to produce shoots varied depending on the culture medium. BAP (2 mg/l) gave the highest response (73.33 - 97.77%) with the regeneration of 3.7 shoots per explant with hypocotyl and 5.8 shoots per explant with epicotyl. Substitution of BAP at an equimolar concentration with kinetin and TDZ, and incorporation of NAA during shoot bud induction did not show any improvement over that obtained with BAP and promoted callusing to a different degree. The regenerated shoots were readily elongated on the same medium as used for induction and rooted on half-strength MS basal medium without any growth regulators. 62% of the plantlets were successfully acclimatized and potted plants were established in soil with 73% survival rate.