Effects of Red and Blue Light-Emitting Diodes on Callus Induction, Callus Proliferation, and Protocorm-Like Body Formation from Callus in Cymbidium Orchid

Abstract

The effects of light generated by red and blue light-emitting diodes (LEDs) on callus induction from protocorm-like body (PLB) segments, callus proliferation and PLB formation from callus in Cymbidium orchid were investigated. The cultures were placed in 'LED PACK 4' incubators under different ratios of red and blue LED light (100% red LEDs, 75% red LEDs+25% blue LEDs, 50% red LEDs+50% blue LEDs, 25% red LEDs+75% blue LEDs, and 100% blue LEDs) at 45 .MU.mol m-2s-1 with a 16-h photoperiod or put under plant growth fluorescent (PGF) light with the same light intensity and photoperiod. Among the treatments, 100% red LEDs was the most effective for callus induction from PLB segments. Callus proliferation was best in the 75% red LEDs+25% blue LEDs treatment but was not significantly different from that in PGF light. The highest PLB formation from callus was obtained in 25% red LEDs+75% blue LEDs. The results suggested that LEDs are the effective light source for callus induction, callus proliferation and PLB formation from callus in Cymbidium orchid.