In recent years, the area of facility horticulture in China has developed rapidly, and the technology of light environment control lighting for plant growth has attracted much attention. Facility horticultural lighting technology is mainly applied in two aspects:
1. Supplementary illumination for plant photosynthesis when the amount of sunshine is small or the duration of sunshine is short.
2. Induced lighting as photoperiod and photomorphogenesis of plants.
Traditional artificial light sources generate too much heat, such as LED plant lights, air can be recycled, too much heat and moisture can be removed, electric energy can be efficiently converted into effective photosynthetic radiation, and ultimately into plant matter. The results show that the growth rate and photosynthetic rate of lettuce can be increased by more than 20% by using plant growth lamp. It is feasible to use LED in plant factories.
Compared with fluorescent lamp, mixed-wavelength LED plant supplementary lamp can significantly promote vegetable growth and development, and improve morphological indicators. The specific wavelength of LED can affect the flowering time, quality and duration of plants. Some wavelengths of LED can increase the number of flower buds and flowers; some wavelengths of LED can reduce the flowering response, regulate the length of pedicels and flowering period, which is conducive to the production and marketing of cut peanuts. Thus, the flowering and subsequent growth of plants can be regulated by LED regulation.
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, suitable for photosynthesis and morphogenesis, small size, light weight, long life, high safety, reliable record and no environmental pollution. Compared with other light sources, such as cold white fluorescent lamp, high pressure sodium lamp and metal halogen lamp, LED can convert light energy into photosynthetic active radiation more effectively. In addition, it has the characteristics of long life, small size, light weight and solid state, so it has been paid more attention in the cultivation of ground and space plants in recent years.
