Plant development is strongly influenced by the light quality, which refers to the color or wavelength reaching a plant's surface (Johkan et al., 2010). Red (R) and blue (B) lights have the greatest impact on plant growth because they are the major energy sources for photosynthetic CO2 assimilation in plants. Past studies examined the action spectra for photosynthesis of higher plants. It is well known that action spectra have action maxima in the B and R ranges (Cosgrove, 1981 and Kasajima et al., 2008). Combined RB LED lights were proven to be an effective lighting source for producing many plant species, including lettuce, in controlled environments