Due to the absorption of covering materials in greenhouses and greenhouses, the ultraviolet part of sunlight will be greatly reduced. An important feature of the greenhouse growth system is the lack of mid-wave ultraviolet UV-B (280~320nm) in natural sunlight. The physiological effects of this phenomenon are unclear.
Plants often develop a thick leaf epidermis or waxy layer under sunlight, which is protected against UV radiation. Greenhouse plants have never developed such a protective layer because the greenhouse cover material protects them from UV radiation (Leonardi et al., 2000).
The spectrum received by the facility plants can filter out spectra of specific wavelengths through the covered functional plastic film (changing the chemical composition). Tsormpatsidi et al. (2008) studied the growth of lettuce and the production of anthocyanins, flavonoids and phenols under different UV radiation penetration membranes. The film includes a completely UV transparent film, a film that can transmit 320m, 350m, 370m, and 380m, and a film that does not transmit UV radiation at all. The results show that the dry weight of lettuce under a completely UV-opaque film (UV400) is 2.2 times that of lettuce grown under a completely UV-permeable film; on the contrary, the anthocyanin content of lettuce under a completely UV-permeable film is approximately UV 8 times the lettuce under the completely impermeable membrane.
Casal et al. (2009) studied the effect of UV radiation on the yield of two strawberry varieties. It was found that the yield of the two strawberries increased by 30% and 20% without UV radiation. The use of UV-B blocking film delayed the ripening of strawberry fruits, and the average weight of a single fruit was also the highest without UV radiation.
Studies have found that supplementation of UV-B radiation affects the growth, quality and physiological characteristics of non-heading Chinese cabbage. Supplementing an appropriate amount of UV-B radiation can effectively control plant growth and increase vitamin C content, but will not cause a significant decrease in yield. The artificially controlled UV-B light source is applied to supplement the UV-B radiation technology in the facility, which can improve the quality of fruits and prevent the growth of plants; it can reduce the use of chemical methods to prevent the growth of vegetables and improve the quality of vegetables, which is an important guarantee for the production of green organic food.
However, so far, there are few reports on the regulation mechanism of medium and long wavelength UV-A and UV-B on the nutritional quality of facility vegetables, especially antioxidants, and there is a lack of effective UV light environmental management and regulation technology. LED has been used as an energy-saving light source for vegetable cultivation in artificial light facilities. The application potential of UV-LED and the biological effects of light quality and lamps are particularly in need of in-depth research and development.
Changes in MDA, AsA and UV-B absorbing substances are the main reason for the improvement of kidney bean resistance. Many studies have involved photosynthetically active radiation (400~700nm) in changing the sensitivity of plants to UV-B (280-320nm) and photomorphogenesis. A number of studies have been done, but no studies have involved the interaction of UV-A (320~400m), UV-B and PAR. High PAR-UV-B ratio and UV-A-UV-B ratio can reduce UV-B damage of land plants and aquatic plants. Growth room and greenhouse studies conducted under low PAR, UV-A and high UV-B radiation often exaggerate UV-B damage.
The spectral balance between PAR, UV-A, and UV-B is important for determining plant sensitivity in the field (Krizek, 2004). Generally, plant biomass and plant height decrease, with increasing PAR and UV-B. The protective effect of high-strength PAR on the increased UV-B may indirectly increase leaf thickness, yellow-like concentration and phenolic concentration, and protect plants from UV damage. DAR light quality is very important. Blue light and UV-A together play an important role in repairing DNA damage. The working relationship between UV-A and UV-B needs to be studied systematically.
The regulation of UV on the growth and quality of facility plants
Due to the absorption of covering materials in greenhouses and greenhouses, the ultraviolet part of sunlight will be greatly reduced. An important feature of the greenhouse growth system is the lack of mid-wave ultraviolet UV-B (280~320nm) in natural sunlight. The physiological effects of this phenomenon are unclear.
Plants often develop a thick leaf epidermis or waxy layer under sunlight, which is protected against UV radiation. Greenhouse plants have never developed such a protective layer because the greenhouse cover material protects them from UV radiation (Leonardi et al., 2000).
The spectrum received by the facility plants can filter out spectra of specific wavelengths through the covered functional plastic film (changing the chemical composition). Tsormpatsidi et al. (2008) studied the growth of lettuce and the production of anthocyanins, flavonoids and phenols under different UV radiation penetration membranes. The film includes a completely UV transparent film, a film that can transmit 320m, 350m, 370m, and 380m, and a film that does not transmit UV radiation at all. The results show that the dry weight of lettuce under a completely UV-opaque film (UV400) is 2.2 times that of lettuce grown under a completely UV-permeable film; on the contrary, the anthocyanin content of lettuce under a completely UV-permeable film is approximately UV 8 times the lettuce under the completely impermeable membrane.
Casal et al. (2009) studied the effect of UV radiation on the yield of two strawberry varieties. It was found that the yield of the two strawberries increased by 30% and 20% without UV radiation. The use of UV-B blocking film delayed the ripening of strawberry fruits, and the average weight of a single fruit was also the highest without UV radiation.
Studies have found that supplementation of UV-B radiation affects the growth, quality and physiological characteristics of non-heading Chinese cabbage. Supplementing an appropriate amount of UV-B radiation can effectively control plant growth and increase vitamin C content, but will not cause a significant decrease in yield. The artificially controlled UV-B light source is applied to supplement the UV-B radiation technology in the facility, which can improve the quality of fruits and prevent the growth of plants; it can reduce the use of chemical methods to prevent the growth of vegetables and improve the quality of vegetables, which is an important guarantee for the production of green organic food.
However, so far, there are few reports on the regulation mechanism of medium and long wavelength UV-A and UV-B on the nutritional quality of facility vegetables, especially antioxidants, and there is a lack of effective UV light environmental management and regulation technology. LED has been used as an energy-saving light source for vegetable cultivation in artificial light facilities. The application potential of UV-LED and the biological effects of light quality and lamps are particularly in need of in-depth research and development.
LED has the incomparable advantages of other electric light sources: energy saving and environmental protection, cold light source, long service life, small size, pure light quality, high light efficiency, rich wavelength types, easy combination of spectral energy, convenient modulation and other outstanding advantages, which can be illuminated at close distances For plants, a multi-layer three-dimensional cultivation system can be used. LED has become an ideal light source for greenhouse supplement light and facility artificial light vegetable cultivation, and it also provides the possibility to explore the physiological effects of monochromatic light.
Changes in MDA, AsA and UV-B absorbing substances are the main reason for the improvement of kidney bean resistance. Many studies have involved photosynthetically active radiation (400~700nm) in changing the sensitivity of plants to UV-B (280-320nm) and photomorphogenesis. A number of studies have been done, but no studies have involved the interaction of UV-A (320~400m), UV-B and PAR. High PAR-UV-B ratio and UV-A-UV-B ratio can reduce UV-B damage of land plants and aquatic plants. Growth room and greenhouse studies conducted under low PAR, UV-A and high UV-B radiation often exaggerate UV-B damage.
The spectral balance between PAR, UV-A, and UV-B is important for determining plant sensitivity in the field (Krizek, 2004). Generally, plant biomass and plant height decrease, with increasing PAR and UV-B. The protective effect of high-strength PAR on the increased UV-B may indirectly increase leaf thickness, yellow-like concentration and phenolic concentration, and protect plants from UV damage. DAR light quality is very important. Blue light and UV-A together play an important role in repairing DNA damage. The working relationship between UV-A and UV-B needs to be studied systematically.