APPLICABILITY OF A NEWLY DEVELOPED FIELD EMISSION LAMP FOR PROLIFERATION OF CYMBIDIUM PLB IN VITRO

The aim of this study is to examine the effect of a field emission lamp (FEL) on the proliferation of the protocorm-like body (PLB) of Cymbidium cultured in vitro. Experiment 1: comparisons between several light sources (red and white FEL, fluorescent tube, red LEDs and cool cathode fluorescent lamps (CCFL)) were performed using PLBs of Cymbidium Waltz ‘Idol’. Experiment 2: comparison between white FEL and CCFL was performed using PLBs of Cymbidium tracyanum, C. Waltz ‘Idol’ and C. Pure Propose ‘Wedding’. Cultures were maintained at 25°C with a 16-h photoperiod of 14 µmol m^-2 s^-1 for 42 days. In C. Waltz ‘Idol’, the number of PLB and root formation rate were similar regardless the light sources. The colour of Cymbidium PLB cultured under red LEDs was yellowish green at 42 days after culture, suggesting low light intensity. However, with white FEL at the same PPFD value, the colour of PLBs was normal green. After 42 days, the fresh weight of the PLBs of the three orchids was significantly higher with FEL than CCFL. The number of PLBs was similar with white FEL and CCFL, except for C. tracyanum, where more PLBs were produced with white FEL than CCFL. These results suggest that this newly developed light source, an FEL with a nano-diamond (ND) emitter, could be used as an energy efficient light source for the propagation of Cymbidium PLBs in vitro.