In Part 2 of this report, we analyzed the spectrum distribution of several high intensity discharge lamps, in which the spectrum values were multiplied by the average values for 4 different photosynthesis curves developed by McCree(1972) and Inada(1976), and we calculated the photoelectric conversion efficiency expressed as the plant growth radiant efficiency. As a result, we confirmed the high effectiveness of high pressure sodium lamps for plant growth within the PAR range of wavelengths, and concluded that a metal halide lamp 3,500 K (150 W high color rendering index type) was a suitable light source for indoor maintenance of ornamental plants. We also analyzed the light quality within the PAR range of different artificial light sources, by using the R/B and R/FR ratios as a reference to photomorphogenesis.