Effect of LED supplementary light on the nutritional quality of fruits and vegetables

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

The phenolic substances, flavonoids, anthocyanins and other substances contained in fruits and vegetables not only have an important impact on the color, flavor and commodity value of fruits and vegetables, but also have natural antioxidant activity, which can effectively inhibit or eliminate free radicals in the human body. The use of LED blue light to supplement light can significantly increase the anthocyanin content of eggplant skin by 73.6%, while the use of LED red light and red and blue combined light can increase the content of flavonoids and total phenols; blue light can promote the content of lycopene, the accumulation of flavonoids and anthocyanins, the combination of red and blue light can promote the production of anthocyanins to a certain extent, but inhibit the synthesis of flavonoids; compared with white light treatment, red light treatment can significantly increase the anthocyanin content of lettuce shoots content, but the content of anthocyanins in the shoots of lettuce treated with blue light was the lowest; the total phenolic content of green leaf, purple leaf and red leaf lettuce had larger values under white light, red and blue combined light and blue light treatment, but were all under red light treatment. is the lowest value; Supplementing LED ultraviolet light or orange light can increase the content of phenolic compounds in lettuce leaves, while supplementing green light can increase the content of anthocyanins. Therefore, the use of LED supplementary light is an effective way to regulate the nutritional quality of fruits and vegetables in facilities.