There are people who say far red/infrared spectrum is not a player in photosynthesis, but this old person is inclined to believe that it has a synergistic effect when combined with other lighting. Some people also believed that green never played any appreciable role as well but that has been proven by researchers like Dr. Bugby to be incorrect, and he is currently studying the effects of far red wavelengths on photosynthesis. I think as wide a spectrum as possible delivered as efficiently as possible is the ticket.