Effects of red light on the growth and morphology of potato plantlets in vitro: Using light emitting diodes (LEDS) as a light source for micropropagation

Red light emitting diodes (LEDs, peak wavelength: 660 nm) and white fluorescent lamps were used as light sources for growth of potato plantlets in vitro. Red (630-690 nm) photon flux (R-PF) on the empty culture shelf were adjusted at 11, 15, 28, 47 or 64 μ.mol m^-2 s^-1. Photosynthetic photon flux (PPF) on the empty culture shelf was adjusted at 100 μ.mol m^-2 s^-1 in all the treatments. Potato plantlets were cultured on Murashige &Skoog (1962) medium with or without sugar at an air temperature of 25°C and a photoperiod of 16 h. Shoot length and chlorophyll concentration of the plantlets increased with increasing R-PF, while there were no significant differences in dry weight and leaf area of the plantlets regardless of R-PF levels. Red light affected the morphology rather than the growth rate of potato plantlets in vitro. Red LEDs can be used for controlling plantlet morphology in micropropagation.