The effects of different light qualities on rapeseed (Brassica napus L.) plantlet growth and morphogenesis in vitro

The light sources generally used for in vitro plant cultures are fluorescent lamps. To select a more efficient light source, the present study evaluated the effects of different light qualities on the growth and morphogenesis of rapeseed (Brassica napus L.) cultivar Westar plantlets in vitro. The plantlets were exposed to 60 μmol m−2 s−1 photosynthetic photon flux (PPF) for a 12 h photoperiod under the following six different light qualities: fluorescent lamps (FL), monochromic blue light-emitting diodes (LEDs) (B), monochromic red LED (R), and three mixtures of B plus R (3:1, 1:1, 1:3) LED. The proliferation rate was greater in plantlets that were cultured under B light than those under FL. The differentiation rate, fresh mass, dry mass, concentration of chlorophyll a, soluble sugar concentration, stem diameter, leaf stomata abaxial surface length, adaxial surface stomata frequency and transplantation survival rate were greater in plantlets that were cultured under B:R = 3:1 light than under FL. The concentration of starch and the spongy tissue length were higher in plantlets cultured under R light than those under FL. The B:R = 3:1 LED light was suitable for rapeseed plantlet growth in vitro and can be used as a priority light source in the rapeseed culture system according to its differentiation rate, proliferation rate, growth rate, and transplantation survival rate.