We know light is the basic environmental factors of plant growth. It is not only the basic energy of photosynthesis, but also an important regulator of plant growth and development. It is not only affected by the amount of light or light intensity (photon flux density, PFD), but also by the light that is different wavelengths and radiation and their different composition ratio.
Solar spectrum can be roughly divided into three parts: ultraviolet radiation, visible light or photo synthetically active radiation and infrared radiation.
Ultraviolet radiation: ultraviolet, UV<400nm, including UV-A320~400nm; UV-B280~320 nm; UV-C<280nm, 100~280nm.
Visible light or photo synthetically active radiation: photo synthetically active radiation，PAR, 400~700nm. Including blue light-400~500nm, green light-500~600nm, red light-600~700nm.
Infrared radiation (IR)-700~800nm.
Plants can perceive the subtle changes in light quality, light intensity, light duration and direction in the growing environment, and initiate the changes in physiological and morphological structures necessary to survive.
Blue light, red light and far red light play a key role in controlling plant light form. Phyto chrome, (Phy)、crypto chrome (Cry) and photo tropin(Phot) , these photo receptors accept light signals and cause plant growth and development changes by signal transduction.
Red Light (600~700nm)
In the red light, plants make photosynthesis, the material can promote plant growth, especially the growth of plant stems and promoting carbohydrate synthesis, but also conducive to the synthesis of sugar and fruits and vegetables VC. Red light is best for flowering and seed production.
Blue Light (400~500nm)
Blue Light can enhance the activities of the chloroplast, to prevent plant leggy, but on the other hand will inhibit photosynthesis, more suitable for meat plants, stems and leaves. Blue light is best for promotiong the stem and leaf.
UV Light (395~400nm)
UV on the growth of plants have a stimulating effect, can increase crop yield, promote protein, sugar, acid synthesis. UV light is good for seeding and sterilization.
IR Light (730~730nm)
IR light can provide heat to supply of crop growth and development, in the infrared radiation, the fruit can make the maturity of convergence. IR light is good for plant bloom.