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This study reports the in vitro germination of self-pollinated pod of Vanilla siamensis, native to Thailand. The aim of the present work is to determine the effect of culture media and plant growth regulators on seed germination and plantlet regeneration. The vanilla seeds were asymbiotically germinated on different culture media under aseptic conditions. The results showed that, New Dogashima medium (NDM) supplemented with 2% (w/v) sucrose, 15% (v/v) coconut water (CW) and 0.7% (w/v) agar gave the highest levels of seed germination at 10.1%. The fastest and highest percentage seed germination was achieved using NDM supplemented with 2 mg/l gibberellic acid (GA 3). Seeds on this culture medium germinated within 7-8 weeks in comparison with 10-11 weeks on culture medium without plant growth regulators. Protocorms were transferred to different culture media with various concentrations of 6benzyladenine (BA) to assess the protocorm development. The results revealed that ½ Murashige and Skoog (½ MS) medium gave the higher result in survival rate of protocorm than NDM. ½ MS medium with 0.5 mg/l BA was suitable for shoot formation. Plantlet development was completed after subculturing on ½ MS medium supplemented with 0.5 mg/l α-naphthaleneacetic acid (NAA) for 8 weeks and successfully acclimatized at 91.7%. The protocol outline here can be used for mass propagation of this endangered species and used as a guideline for improvement of V. siamensis and its in vitro conservation.

Viability of Grammatophyllum speciosum seeds was evaluated by a TTC (2,3,5-triphenyl tetrazolium chloride) test. The seeds were then asymbiotically germinated on different agar media under aseptic conditions. The results showed that keeping the seeds in the dark at 30°C for 1 day gave 99% of red staining embryos (referred to as viable). After sowing the seeds on half-strength Gamborg's B5 medium supplemented with 0.1% activated charcoal (AC) for 30 days, germination of those seeds was observed. Half-strength MS medium (½ MS) supplemented with 1 mg/l 6-benzylaminopurine in combination with 0.5 mg/l α-naphthalene acetic acid, 15% coconut water, 0.2% AC, and 0.7% agar gave the highest percentage of protocorm-like body (PLB) induction and proliferation. The PLBs could be regenerated into complete plantlets with vigorous shoot and root formation on ½ MS medium without any plant growth regulators. The survival rate of plantlets was 70% after hardening off in the greenhouse for 1 month.