The main objective of this study was to carry out tissue culture of Gracilaria verrucosa for production of adequate seedlings with desirable qualities for mass seaweed production that will sustain a viable agar industry in Kenya. Four tissue culture experiments were carried out during the present study period, with emphasis on regeneration, contamination and survival of cultured explants. Explants were excised from native G. verrucosa samples from Kibuyuni study site in south coast Kenya and surfaced sterilized with 10% sodium hypochlorite solution before being cultured in Murashige and Skoog (MS) basal medium in combinations with varied plant growth regulators such as; gibberelic acid (GA3) kinetin (6-furfurylamino) purine, 2,4-dicholorophenoxyacetic acid (2,4-D), and indole-3-acetic acid (IAA) in concentration ranges of 0, 0.5,1.0, and 1.5 mg L−1. Culture medium without PGRs was used as the control.
Experiment 1 was monitored for period of 16 weeks while experiment 2 for 20 weeks. Explants cultured in medium supplemented with IAA at 0.5 mg L-1 concentration level exhibited highest shoot regeneration efficiencies of 67, 100 and 67 % after 8, 12 and 16 weeks of culture period respectively in experiment 1, and shoot regeneration efficiencies of 0, 67, 100 and 100% after 8, 12, 16 and 20 weeks of culture periods respectively in experiment 2. Similarly, explants cultured on medium with GA3 enrichment at 1.5 mg L-1 concentration level in experiment 1 exhibited the highest shoot regeneration efficiencies of 100, 33 and 67 % during 8, 12 and 16 weeks of culture periods, and 100% shoot regeneration efficiency in all respective culture periods in experiment 2. The results suggest that tissue culture of G. verrucosa is possible if contamination of cultures can be minimized through frequent observation of the cultures.