Light is the basic environmental factor for plant growth and development. It is not only the basic energy source of photosynthesis, but also an important regulator of plant growth and development. The growth and development of plants is not only restricted by the amount or intensity of light (photon flux density, photonfluxdensity, PFD), but also by the quality of light, that is, light and radiation of different wavelengths and their different composition ratios.

Plant Lighting Knowledge: 5 Monochromatic Lights That Affect Plant Growth

The solar spectrum can be roughly divided into ultraviolet radiation (ultraviolet, UV<400nm, including UV-A320~400nm; UV-B280~320nm; UV-C<280nm, 100~280nm), visible light or photosynthetically active radiation (PAR, 400~700nm, including blue light 400~500nm; green light 500~600nm; red light 600~700nm) and infrared radiation (700~800nm). UV-C and most UV-B do not reach the Earth's surface due to absorption by ozone in the stratosphere (stratosphere). The intensity of UV-B radiation reaching the ground varies with geography (altitude and latitude), time (day time, seasonal changes), meteorology (the presence of clouds, thickness, etc.) and other environmental factors such as air pollution .

Plants can detect subtle changes in light quality, light intensity, duration and direction of light in the growing environment, triggering changes in physiological and morphological structures necessary for survival in this environment. Blue, red, and far-red light play key roles in controlling plant photomorphogenesis. Photoreceptors such as phytochrome (Phy), cryptochrome (Cry) and phototropin (phototropin, Phot) receive light signals and trigger changes in plant growth and development through signal transduction.

The monochromatic light mentioned here refers to light within a specific wavelength range. The wavelength bands of the same monochromatic light used in different experiments are not completely consistent, and often have different degrees of overlap with other monochromatic lights with similar wavelengths, especially before the emergence of LED light sources with good monochromaticity. In this way, different and even contradictory results will naturally result.