Uncovering LED light effects on plant growth: new angles and perspectives: LED Light for Improving Plant Growth and Energy Use Efficiency

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. LED (Light emitting-diode) lamps are a promising technology that has tremendous potential to improve irradiance efficiency and to replace traditionally used horticultural lighting (Kozai et al., 2015). LED provides precise light spectrum and close illumination. Their small size, durability, long lifetime, and cool emitting temperature are more suitable for plant-based uses than many other light sources. This project aims to investigate energy use efficiency and photosynthesis with the evaluation and improvement of protected horticulture system. At the initial phase the effects of different supplemental light including LED light on plant growth and photosynthesis in lettuce have been studied, the higher luminous efficiency and positive impact for plant’s growth showed the great potential of LED facilities compared with other artificial light and indicated that it is the most appropriate light resource at this stage. Claims of 50% energy savings for similar biomass yields are now obtained in the study. Further, extending the species of crops for LED faming system have been used for potential maximum efficiency during plant growth and development (Lu et al., 2015).The results also showed lettuce plants grown under the continuous combined red, green and blue LED light exhibited a remarkable decrease of nitrate contents at 24 h compared to other LED light treatments. In addition, red and blue light was more effective in facilitating lettuce plant growth than white LED light (Bian et ac., 2016). Moreover, continuous LED light at 24 h significantly increase phenolic compound concentrations.