A new technique for coconut (Cocos nucifera L.)
germplasm collection was evaluated in the laboratory and tested in the field
in Indonesia. The technique involved the non-sterile isolation of embryos, and
incubation in sterile ascorbic acid solution (1 mg L –1 ) at 5 1˚C
in the dark. During this incubation period the embryos could be transported
and/or stored for a period of up to 4 days without embryo viability loss.
Following this period the embryos were surface sterilised with sodium
hypochlorite (1.5% w/v) for 20 min, washed with sterile water and
cultured in a liquid Y3 basal nutrient medium supplemented with Morel and
Wetmore vitamins, sucrose (175 mM) and activated charcoal (2.5 g L –1 ).
After two weeks the embryos were subcultured onto a solid medium of similar
constitution to encourage germination. Germinated embryos grew and produced
healthy plants with normal morphology. Despite mild chilling injury as
indicated by elevated ethylene production and solute leakage, the transported
embryos retained viability with normal morphology. Using the low-temperature
incubation treatment, the microorganism density in the ascorbic acid solution
was kept low while that around other embryos kept at higher temperatures
(25˚C) increased. Even though embryos were exposed to a low-temperature
treatment for up to 4 days they were able to germinate (95% viable) and
grow in an identical fashion to freshly cultured embryos.