Regeneration of plantlets from shoot apex-derived callus and "calloid" cultures of a local taro [Colocasia esculenta var. antiquorum cv. Keladi Birah] cultivar, was expedited by treatment with high levels of spermine. The total time taken, from culture of primary shoot apices on modified Linsmaier and Skoog medium supplemented with trichlorophenoxyacetic acid and kinetin, to complete plantlet regeneration, was reduced by 2-16 weeks, when the callus and "calloid" cultures were treated with 0.01, 0.1 and 1 mM spermine. Furthermore, the number of plantlets produced per gram callus increased from 25 to 55. On media supplemented with arginine and ornithine, no callus was initiated from expiants and no plantlets differentiated from pre-established callus.
In vitro growth and multiplication of taro [Colocasia esculenta var. antiquorum cv. Keladi Birah] was improved considerably, when primary shoot apices were cultured on two modifications of Linsmaier and Skoog [1965] medium, containing 5.5 mg 1(-1) naphthaleneacetic acid and 0.2 mg 1(-1) kinetin or 1.85 mg 1(-1) naphthaleneacetic acid and 2 mg 1(-1) kinetin and supplemented with 10(-4) or 10(-3) mol·1(-1) of polyamine spermine or either of the precursors of polyamine putrescine-arginine and ornithine. Plantlets were regenerated directly from primary shoot apices, axillary buds and protocorm-like bodies [PLB]. Frequency of plantlet regeneration, rate of development and growth in height of main plantlets were enhanced by the addition of arginine and ornithine to the media. Secondary plantlet formation from axillary buds and PLB were promoted by spermine and arginine respectively.