Abstract:
In vitro somatic embryogenesis is the most important means of mass propagating high
quality-planting materials in Cocos nucifera L. (coconut). Despite long-term research,
undertaken to develop suitable culture conditions for in vitro somatic embryogenesis
and plant regeneration from a local variety (Sri Lanka Tall) of coconut. It also
included studies on markers for early detection of tissues with embryogenic potential,
comparative histological and biochemical studies on zygotic and in vitro somatic
embryos at different developmental stages.
During the study, embryogenic callus was initiated from plumule explants excised
from pre-cultured mature zygotic embryos. The basal culture media, 72, Y3 and MS
were found to be suitable for callogenesis when supplemented with appropriate
concentration of 2,4-D (24 pM). However, the adsorption capacity of activated
charcoal present in the medium determines the level of freely available 2,4-D in the
medium and therefore it plays a crucial role in callogenesis. Under the most suitable
combination of charcoal and 2,4-D (0.25 % Pharmacos charcoal with 24 pM 2,4-D
and 0.1 % BDH, acid-washed charcoal with 100 pM 2,4-D), about 50 % plumule
explants produced embryogenic callus. The callusing frequency in charcoal-free
media was found to be lower (about 29 %) than that of charcoal-containing media.
Attempts were made to produce friable callus for the establishment of cell
suspensions. However, it was not possible to obtain friable callus during the course of
the study and thus fine suspension cultures could not be established.
