In controlled environment agriculture, energy is the predominant factor in production costs. Lighting is the one major consumers of energy. Commercial crop production in greenhouses can be enhanced by supplemental lighting which provides low moderate intensity light levels to increase photosynthesis and plant growth. Traditionally, horticultural lights were high-intensity discharge lamps such as high-pressure sodium (HPS), metal-halide (MH), and mercury (HPMV). The disadvantages of these lamps are high-energy costs, heat generation and suboptimal spectrum for photosynthesis
