Abstract:
Dioscorea alata L. (Yam) is a member of genus Dioscorea and monocotyledonous plant
belonging to the Dioscoreaceae family which comprises about 600 species. D. alata is an
important corp plant that produces tuberous roots used as a source of food and medicine.
Inefficiency of traditional methods of propagation and lack of planting materials are the main
constraints for implementing large-scale cultivation. The purpose of this study was, therefore,
to develop a micropropagation protocol for D. alata L. from shoot tip and nodal explants.
Explants were sterilized using different concentrations of NaOCl for different time exposure.
MS culture media supplemented with different types and concentration of auxins and
cytokinins were used for culture initiation, shoot multiplication and root induction. Sodium
hypochlorite (NaOCl, 5.2% of active chlorine) at a concentration of 5 and 2 % at exposure
time of 5 and 20 minutes gave 76.60±0.36%, of survived explants for nodal and 72.66±0.85%
for shoot tip respectively. The initiation media with a combination of 4x4x2x2 factorial; and
multiplication of 3x3x2x2 factorial were used. From these, BAP of 1.5 mg/l + NAA of 1.0 mg/l
gave 93.2% for nodal and BAP of 1.0 mg/l + NAA of 1.0 mg/l gave 87.1% for shoot tip was
found to be an optimum concentration for shoot induction. The combination of 2.0mg/l KIN,
1.0mg/l BAP and with 0.5mg/l NAA and 2.0mg/l KIN, 0.5mg/l BAP and with 0.5mg/l NAA was
found to be the optimum concentration yielding 8.4± 0.21% and 9.5± 0.29% shoots per
explants for shoot tip and nodal respectively for shoot multiplication. Half strength MS
medium with 2.0 mg/l IBA gave the highest rooting percentage and with 2.0mg/l NAA gave
optimum root number and length. Up on acclimatization and transplanting, 90% survival
efficiency was observed on soil mix ratio of 2:2:1 decomposed coffee husk, sand and red soil
respectively. There were no observable variations with respect to morphology and growth
characteristics to the greenhouse raised parent plant. The results obtained in this study permit
the development of mass propagation protocol that could enable large scale commercial
production of this highly demanded Dioscorea cultivar and provide a possible system towards
genetic improvement of the crop.