The effect of LED fill light on the nutritional quality of fruits and vegetables

Proteins, sugars, organic acids, and vitamins contained in fruits and vegetables are beneficial nutrients for human health. Light quality can affect the content of VC in plants by regulating the activity of VC synthesis and decomposing enzymes, and it regulates protein metabolism and carbohydrate accumulation in horticultural plants. Red light promotes the accumulation of carbohydrates, and blue light treatment is conducive to protein formation. The red-blue combination has a significantly higher effect on the nutritional quality of plants than monochromatic light. Supplementing LED red or blue light can reduce the nitrate content in lettuce, supplementing blue or green light can promote the accumulation of soluble sugar in lettuce, supplementing infrared light is beneficial to the accumulation of VC in lettuce. Complementary blue light can promote the increase of VC content and soluble protein content of tomato; red light and red-blue light treatment can promote the sugar and acid content in tomato fruit, and its sugar to acid ratio is highest under the combination of red and blue light treatment; The combination of red and blue light can promote the increase of VC content in cucumber fruits.

Phenolic substances, flavonoids, anthocyanins and other substances contained in fruits and vegetables not only have an important influence on the color, flavor and commercial value of fruits and vegetables, but also have natural antioxidant activity, and can effectively inhibit or eliminate human free radicals. The use of LED blue light to make the anthocyanin content of eggplant skin significantly increased by 73.6%, while the use of LED red light, red and blue light combination can increase the content of flavonoids and total phenols; blue light can promote lycopene in tomato fruit. The accumulation of flavonoids and anthocyanins, combined with red-blue light, promotes the production of anthocyanins to a certain extent, but inhibits the synthesis of flavonoids. Compared with white light treatment, red light treatment can significantly increase the anthocyanins of lettuce aboveground. But the content of anthocyanin in the aerial parts of lettuce with blue light is the lowest; the total phenolic content of green leaves, purple leaves and red leaf lettuce have larger values ??under white light, red and blue combined light and blue light treatment. But under the red light treatment, it is the lowest value; supplementing with LED ultraviolet or orange light can increase the content of phenolic compounds in lettuce leaves, while supplemental green light can increase the content of anthocyanins. Therefore, the use of LED supplement light is an effective way to regulate the nutritional quality of fruits and vegetables.