CALLUS INITIATION, PROMOTION AND PLANTLET REGENERATION FROM DIFFERENT PARTS OF THE SHOOT TIP OF PRITCHARDIA ORNAMENTAL PALMS GROWN IN VITRO.

Plantlets of Pritchardia kaalae Rock have been initiated from clonal explants via callus. Shoot tips (St) of size 3-4 mm, leaf primordia of different stages (Lp), cork distal to the shoot tip (Ck), and the basal part of the leaf primordia attached to its distal cork (Lc), were all grown on Murashige and Skoog (MS) medium supplemented with a high concentration of 2,4-D (100 mg/l) + 2ip (3 mg/l), NaH₂PO₄ (170 mg/l), myo-inositol (100 mg/l) and activated charcoal (3 g/l) at

pH : 5.7, incubated in complete darkness at 27°C.

After initiation callus was randomly distributed on 5 different media, which were a combination between different concentrations of 2,4-D and 2ip added to MS medium plus the previously mentioned additives with the same concentrations including a control, with the aim of promoting callus growth. Media that proved to be most promotive (measured by the change in callus diameter) for callus derived from Lp tissues was that of MS supplemented with 2,4-D (10 mg/ l) + 2ip (30 mg/l) and the control. Callus from these media was alternately subcultured on MS + 2,4-D (10 mg/l) + 2ip (30 mg/l) or on the control, still to observe the various changes either in diameter or in the structure of the tissues.

For callus tissues that did not differentiate or show any change in structure all through the previous experiments, such tissues were transfered to MS basal medium with either of the two concentrations of GA₃ (0.1 or 0.01 mg/l), excluding activated charcoal as a last trial to stimulate differentiation.