Regulating radiation quality and intensity using narrow-band leds for optimization of somatic embryogenesis

The objectives of this study were to examine and optimize how radiation quality and intensity influenced both the induction and development of somatic embryos from carrot embryogenic calli using light-emitting diodes (LEDs), which emit precise narrow-band radiation. Somatic embryos induced from carrot embryogenic calli were exposed for 14 days to red and blue radiation at various light intensities. The results pertaining to somatic embryo induction showed that: (1) red radiation at 10 nmol m^-2 s^-1 significantly increased the density of total somatic embryos induced from carrot embryogenic calli; (2) lower and higher intensities of red radiation (1 to 5 mol m ^-2 s^-1 and 20 mol m^{- 2} s ^-1) did not significantly influence the density of induced total somatic embryos; and, (3) increasing the intensity of blue radiation (up to 20 mol m^-2 s^-1) appeared to have reduced the density of induced total somatic embryos. In regard to somatic embryo development, the results showed that: (1) red radiation (up to 20 mol m^-2 s ^-1) had virtually no effect on the development of the carrot somatic embryos; and, (2) blue radiation (10 or 20 mol m^-2 s^-1) exerted positive effects on the development of the carrot somatic embryos, especially in the globular and heart-shaped stages.