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Preparing good quality protocorm like-bodies (PLBs) in-vitro culture of orchids, their regeneration, regeneration, and root formation are important steps in establishing an-vitro protocol of orchids. Murashige and Skoog (MS) medium as a basic medium in the in-vitro culture of the plant was generally applied, utilization of fertilizer as a basic medium for the purpose has few reports. The in-vitro propagation protocol of Dendrobium ‘Gradita 31’ via PLBs, using varied-Growmore (GM) media, was successfully established. Half-strength MS medium containing 1 mg/l Thidiazuron (TDZ) and 0.5 mg/l N6-benzyladenine (BA) was applied in obtan ining high PLB formation and initial proliferation of Dendrobium using shoots as donor explants via repeated subcultures. GM-6 medium (1.6 g/l of 32N:10P:10K) containing 100 ml/l coconut water (CW), was an appropriate medium for growth, proliferation, and regeneration of D. ‘Gradita 31’ PLBs. The medium the stimulated growth rate of PLBs up to 309 mg per month, or equal with 17 PLBs per month, and induced PLB regeneration up to 76% with a high number of regenerated PLBs (5.6 regenerated-PLBs per cluster of PLBs), 3.5 leaves per shoot and 1.19 cm leaf length. The GM-3 medium (200 mg/l 32N:10P:10K+50 mg/l 20N:20P:20K+100 mg/l 6N:30P:30K), augmented with 100 ml/l CW, was a suitable medium for root formation with a shorter period needed for root formation (22.8 days), and 2.4 roots per shoot and 0.76 cm root length, compared to other media. Plantlets were easily acclimatized in ex-vitro conditions with 100% of survivability using Cycas rumphii bulk, and grew well individually after repotting in a mixture medium of C. rumphii bulk andwood charcoal.
Keywords: In-vitro culture, growth, Growmore, proliferation, protocorm like-bodies (PLBs), regeneration, acclimatization and
Dendrobium ‘Gradita 31’.