Protocol optimisation for micropropagation of Ethiopian yam

Abstract

Yam (Dioscorea spp.) is a monocotyledonous tuber forming tropical vine, which belongs to the family Dioscoreaceae, and genus Dioscorea. Yam is well known for medicinal properties, as well as nutritional values. Conventional propagation of yam is limited by low propagation rates; hence, in vitro propagation provides the best alternative to overcome such limitations. The objective of this study was to optimise a protocol for in vitro micro-propagation of Ethiopian yam (D. alata, bulcha variety). Explants were obtained from young leaves of bulcha variety, and sterilised using different concentrations of NaOCl, for different time exposures. Sodium hypochlorite (1%) at 15 minutes exposure time, showed 100% survival of explants. The combination of 0.5 BAP with 1mgl-1 NAA was the best concentration for shoot induction. For shoot multiplication, BAP at 1.5 mg l-1 gave the highest shoots per explants (7.28±0.07), with shoot length of 8.72±0.43 cm. MS medium with 2.0 mg l-1 NAA and 1.5 mg l-1 IBA gave the highest rooting percentage and root number (10.6±0.44), with a root length of 13.80±0.44. In vitro acclimatised plantlets,which were transferred to a greenhouse for hardening, had 90% survival rate on soil medium. Thus, for micropropagation of bulcha yam variety, MS + 1.5 mg l-1 and MS plus 2.0 mg l-1 NAA + 1.5 mg l-1 IBA is the best phytohormonal combination for shoot multiplication and invitro rooting, respectively.