Phalaenopsis bellina is an important indigenous fragrant orchid threatened with extinction. In this study, we evaluated
the effect of medium strength, sucrose, nitrogen (NH4
NO3
) and potato extract on proliferation of P. bellina protocormlike
bodies (PLBs) to improve micropropagation in this species. Optimal treatment for PLBs proliferation rate with an
average fresh weight (FW) of 0.97±0.16 g was obtained through culturing on half strength (½) MS medium containing
20 g/L sucrose, 15 mM NH4
NO3
and 20% w/v potato extract supplemented with 0.8 µM 2,4 dichlorophenoxyacetic acid
(2,4-D). The optimal treatment produced large, healthy and greenish PLBs with reduction in the occurrence of culture
browning. In contrast, treatments with high potato extract (>20% w/v) or NH4
NO3
(>30 mM) concentrations tend to
have inhibitory effect and resulted in low PLBs proliferation rate, with an average FW of 0.77±0.15 g and 0.69±0.15 g,
respectively. Plant regeneration of PLBs was achieved on plant growth regulator (PGR)-free ½ MS medium. In total, 60
healthy PLBs from the optimal treatment were successfully regenerated, acclimatized with 100% survival percentage and
grew well in a mixture of soil, sand and vermicompost (8:4:2 (w/w/w)). With the optimal treatment, PLBs proliferation
rate was enhanced by 27.63%. Our findings offer an improved micropropagation protocol of the endangered P. bellina
for conservation and commercial production.