Effects of light emitting diodes (LEDs) on the in vitro growth of potato and Brazilian ginseng germplasms

The effects of light-emitting diode (LED) illumination on the in vitro growth of nodal segments of potato (Solanum tuberosum) and Brazilian ginseng (Phafia glomerata) germplasms were studied for medium-term in vitro conservation. Nodal segments of three accessions of potato and Brazilian ginseng were cultured under illuminations by blue LEDs (18 µmol m^-2 s^-1), weak blue LEDs (10 µmol m^-2 s^-1), red LEDs (17 µmol m^-2 s^-1), weak red LEDs (8 µmol m^-2 s^-1), and white fluorescent lights (30 µmol m^-2 s^-1: control). After one, three and six months of culture, the in vitro plantlet growths were evaluated. The blue LEDs at 18 µmol m^-2 s^-1 showed a similar efficiency on in vitro plantlet growth compared with the white fluorescent lights at 30 µmol m^-2 s^-1, producing however less quantity of roots. The growths of the plantlets under the weak blue, red and weak red LEDs were reduced in comparison with the white fluorescent lights, particularly in the potato germplasms. It is concluded that, instead of the white fluorescent lights, the blue LEDs can be utilized for slow-growth in vitro conservation of potato and Brazilian ginseng.