1. Study on LED as supplementary lighting for plant photosynthesis
Traditional artificial light sources produce too much heat, such as LED supplementary lighting and hydroponics system, air can be recycled, too much heat and water can be removed, electrical energy can be efficiently transformed into effective photosynthetic radiation, and finally into plant substances. The results show that the growth rate and photosynthetic rate of lettuce are increased by more than 20% by using LED lighting. It is feasible to use led in plant factory.
Compared with fluorescent lamp, LED light source with mixed wavelength can significantly promote the growth and development of spinach, radish and lettuce, improve the morphological index, maximize the biomass accumulation of beet, the most significant accumulation of beet in the root, and produce the highest accumulation of sugar and starch in the root.
Compared with the metal halide lamp, the stem and leaf morphology of pepper and perilla plants grown under the wavelength LED changed significantly, and the photosynthetic rate of plants increased with the increase of light density. The number of stomata of marigold and sage increased with the LED of complex wavelength.
2. LED as induced lighting for plant light cycle and light morphology
Led with specific wavelength can affect flowering time, quality and duration of flowering. Some wavelengths of LED can improve the number of flower buds and flowers; some wavelengths of LED can reduce the reaction of flower formation, regulate the length and flowering period of flower stalks, which is conducive to the production and marketing of cut flowers. It can be seen that led regulation can regulate the flowering and subsequent growth of plants.
3. Research on LED application in aerospace ecological life support system
The establishment of the controlled ecological life support system (CELSS) is the fundamental way to solve the life support problem of long-term manned spaceflight. The cultivation of higher plants is an important component of CELSS, and one of the key lighting.
Based on the special requirements of space environment, the light source used in space higher plant cultivation must have the characteristics of high luminous efficiency, output light wave suitable for plant photosynthesis and morphogenesis, small size, light weight, long life, high safety and reliability record and no environmental pollution. Compared with other light sources such as cold white fluorescent lamp, high pressure sodium lamp and metal halide lamp, LED can effectively convert light energy into photosynthetically effective radiation; in addition, it has the characteristics of long life, small volume, light weight and solid state. Therefore, in recent years, it has been paid more attention in plant cultivation on the ground and in space. The results show that led lighting system can provide illumination with uniform spectral energy distribution, and the efficiency of converting electrical energy into plant light is 520 times higher than that of metal halide lamp.