OPTIMIZATION PROTOCOL FOR IN VITRO ROOTING OF DATE PALM (Phoenix dactylifera L.)

Abstract

A successful tissue culture regime for date palm is determined by the ability of producing healthy in vitro plantlets capable of surviving for acclimatization stage which normally requires a period of incubation in the laboratory. An improved protocol involving paclobutrazol (PBZ) and polyethylene glycol (PEG) has been developed to achieve rooting improvement. Plantlets of date palm cv. Samani, derived from direct somatic embryogenesis, were investigated in two separate experiments. In the first experiment, Plantlets were cultured on 1/2 MS solid medium containing 0.1 mg/l NAA+ 0.1 mg/l BA + 0.5 g/l activated charcoal as a basal nutrient medium supplemented with PBZ at 2, 4, 6 and 8 mg/l combined with sucrose at 30, 40 and 50 g/l. In the second experiment, explants were cultured on 1/2 MS medium+40 g/l sucrose+0.1 mg/l NAA+ 0.5 g/l activated charcoal supplemented with PEG at 0, 2, 4, 6 and 8 g/l. All cultures were incubated under a 16h photoperiod of 4000 lux light intensity at a temperature of 27± 2 °C. The data revealed that, medium contained 4 mg/l PBZ combined with 40 or 50 g/l sucrose increased the thickness of plantlets, also accelerated the root formation and elongation and promoted secondary roots. Addition of PEG at 6 or 8 g/l to the culture medium enhanced plantlets survival during acclimatization stage. Histological study showed that PEG at high concentrations increased the wax deposition on epidermal layer than control plants.