Growth of rice plants under red laser-diode light supplemented with blue light

As a new type of light source for plant production, high-power and high electrical-to-optical power conversion efficiency aluminium-gallium-indium-phosphor (AlGaInP) substrate laser-diode (LD) lamps with the continuous wave output power of 500 mW that have peak emission of 680 nm have been developed. To investigate the effect of red LD on plant growth, rice (Oryza sativa L. cv. Kitaibuki) plants were grown under the red LD light, with supplementing 5% blue fluorescent light. The result showed that rice plants could complete their life cycle under red LD light supplemented with blue light and they reached the harvesting stage earlier than control plants grown under high-pressure sodium (HPS) lamps. However, compared to the control plants, the rice plants grown under red LD light supplemented with blue light, showed 36% decrease in number of tiller spikes and 60% decrease in seed yield at final harvest. Rice plants can be grown using red LD light with supplemental blue light, but the system is new and requires further development and optimization.