Abstract:Background:

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Coconut is a cross pollinating palm, propagated only by seeds. Tissue culture is the only vegetative propagation method available for coconut. Consistent callogenesis was obtained by culturing unfertilised ovaries at -4 stage in CRI 72 medium containing 100 lM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1% activated charcoal. Callusing was improved by application of 9 lM thidiazuron (TDZ). Embryogenic calli were subcultured onto somatic embryogenesis induction medium containing 66 lM 2,4-D. Stunted growth was observed in the somatic embryos after subculture onto CRI 72 medium containing abscisic acid (ABA). Maturation of somatic embryos could be achieved in Y 3 medium without growth regulators. Conversion of somatic embryos was induced by adding gibberellic acid (GA 3 ) to conversion medium containing 5 lM 6-benzyladenine (BA) while 2-isopentyl adenine (2iP) increased the frequency of plant regeneration. A total of 83 plantlets was produced from 32 cultured ovaries.

Abstract:Poor in vitro germination of embryos of exotic varieties was reported as one of the major constraints faced during coconut germplasm exchange programmes. In this study, the effect of genotype, embryo maturity and culture medium on in vitro germination of coconut embryos was investigated.in vitro germination was observed between the selected cultivars, San Ramon Tall (SNRT) (77.48 %), Sri Lanka Red Dwarf (SLRD) (67.28 %), Sri Lanka Green Dwarf (PGD) (71.85 %) and King Coconut (RTB) (52.5 %). Embryo germination percentages were improved in solid media (91.66 % and 92.22 % in 75 g/L and 60 g/L sucrose respectively, p < 0.05) than in liquid media (56.66 % and 60.46 % in 75 g/L and 60 g/L sucrose, respectively) and the sucrose concentration has no effect on germination of affected the germination (p < 0.05) of embryos of PGD and the highest in vitro embryo germination was achieved by culturing embryos of the 12 month old bunch (97.67 %), while the lowest was observed in the 10 month old bunch (52.17 %). Addition of growth hormones favoured root growth of in vitro raised SLRD roots and the number of leaves (p < 0.05) when 10 µM BAP, 10 µM Kinetin and 200 µM NAA were added to the embryo culture medium.

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