Regeneration in African Violet (Saintpaulia ionantha Wendl.) Using Different Leaf Explants, Cytokinins Sources, and Light Regimes

Regeneration from whole leaf, half leaf, and central lamina of African violet (Saintpaulia ionantha Wendl.) positioned with abaxial or adaxial surface in contact with the medium was assessed. Regeneration was also evaluated using 0, 1, 2 or 3 μM TDZ or 0, 10, 20 or 30 μM BA or zeatin under immediate light or 1 or 2-wk dark incubation before exposure to light. Shoots were regenerated irrespective of explant type or position. A 2-wk dark incubation was the most effective in enhancing regeneration from whole leaf and half leaf explants using TDZ or BA. The light regime did not affect regeneration when zeatin or central lamina was used. Cytokinin concentration did not affect regeneration from whole leaf or central lamina cultured with TDZ; half leaf or central lamina cultured with BA; or whole leaf cultured with zeatin. For TDZ, 2 μM and 2-wk dark incubation gave the highest number of regenerants (144 and 214) from whole leaf and half leaf explants, repectively. For BA, the highest number of regenerants from whole leaf explants was recorded for 10 or 20 μM and 2-wk dark incubation and from central lamina using 10 μM and 1 or 2-wk dark incubation or 20 μM and immediate light. For zeatin, 20 μM and immediate light resulted in the highest number of regenerants. Callus was produced on all explants and it exhibited ability to regenerate. All regenerants rooted