PRELIMINARY STUDIES ON in vitro PROPAGATION OF YAM BEAN (Pachyrhizus erosus (L.) Urban)

The regeneration potential of Pachyrhizus erosus using single node culture has been investigated on Murashige and Skoog (1962) (MS) medium alone, and supplemented with each of Benzyladenine (BA), 2-isopentyladenine (2-ip), Kinetin (Kin), Zeatin and Adenine, at a 1 mg/1 concentration. The position effect of the nodes was investigated for hormone sensitivity. The basal medium must be supplemented with hormone for bud burst. Buds were stimulated by a range of cytokinins, but response was not dependent on nodal position. BA, Zeatin and Kinetin, however seem to induce multiple bud proliferation. Callus induction using leaf explants of different physiological ages was investigated on MS medium supplemented with 2, 4-dichlorophenoxyacetic acid (2,4-D); 3 indoleacetic acid (IAA) plus Kin; 1 naphthylacetic acid (NAA) plus Kin; and 2,4-D plus Kin at 1 mg/L concentration. The effect of light on callus initiation was noted. Callus was initiated on MS with 2,4-D plus Kin, also NAA plus Kin incubated in complete darkness. The quantity of callus varied with leaf age. Callus initiated with 2,4-D and Kinetin was placed on MS supplemented with BA using either fructose or glucose as the carbon/energy source, and incubated in light and dark environments. Chlorophyll formation was apparent in callus exposed to light, when the carbon source was fructose. Squash preparations of callus on BA supplemented medium indicated the presence of tracheids. Plantlet regeneration from callus has not yet been achieved.