The growth and development of plants are carried out under full-spectrum sunlight, and different spectral components have different effects on photosynthesis, pigment formation, phototropism and morphogenesis of plants. Red light is beneficial to the accumulation of carbohydrates, while blue light promotes the accumulation of protein and non-carbohydrates. Ultraviolet rays play an important role in the shape, color and quality of plants. There are more ultraviolet rays in mountainous areas and plateaus, which make the stems and leaves of plants short and dark. The effects of different spectra of solar radiation on plants are as follows:
The radiation with the wavelength of (1) greater than 1.00μm is absorbed by plants and converted into heat energy, which affects the temperature and transpiration of plants and promotes the accumulation of dry matter, but does not participate in photosynthesis.
(2) Radiation with wavelength of 1.00 ~ 0.72 micron only affects plant elongation, and radiation with wavelength of 0.72 ~ 0.80 micron is called far infrared ray, which plays an important role in photoperiod and seed formation and controls the color of flowers and fruits.
(3) The red light and orange light with the wavelength of 0.72-0.6 1 micron are strongly absorbed by chlorophyll, which in some cases shows a strong photoperiod effect.
(4) The light with the wavelength of 0.6 1-0.5μ m is mainly green, with low photosynthesis and weak shaping.
(5) The light with the wavelength of 0.5 1 ~ 0.40μ m is mainly blue-violet light, which is strongly absorbed by chlorophyll and melanin, showing strong photosynthesis and shaping effect.
(6) Ultraviolet radiation with the wavelength of 0.40-0.32 micron plays a role in shaping and coloring, making plants shorter, darker in color and thicker in leaves. Ultraviolet ray with wavelength of 0.32-0.28 micron are harmful to most plants. Far ultraviolet with wavelength less than 0.28μm can kill plants immediately.