EFFECTS OF LIGHT EMITTING DIODES ON MICROPROPAGATION OF PHALAENOPSIS ORCHIDS

The effects of light sources from fluorescent bulbs and light emitting diodes (LEDs) were studied on axenic seed germination and micropropagation of Phalaenopsis hybrid. Four types of light sources from LEDs were compared: 100% red, 90% red plus 10% blue, 80% red plus 20% blue and 50% red plus 50% white. After two months from germination, seeds had high germination rate and developed to be protocorms in every type of light sources. The growth and development of protocorms were the highest under 80% red plus 20% blue LEDs in VW medium with 10 g L^-1 sucrose in 4 months after germination. For micropropagation of Phalaenopsis hybrids, the in vitro flower-stalk node was cultured for shoot production and PLBs induction under the same type of light sources. The results showed that the highest number of shoots were obtained under 90% red plus 10% blue LEDs, the shoot tips which excised from young shoots had most PLBs induction 48% under the red and blue LEDs. The PLBs multiplication showed the highest fresh weight under red and blue LEDs. The last experiment was studied on the effects under LEDs of light sources on plantlet growth. After cultured for 4 months, the plantlets had more average fresh weight, height and leaf length than in fluorescent light.