Construction and Application of LED Grow Light Spectrum

The growth and development of plants are significantly affected by the light quality and its different composition ratios. The light formula mainly includes several factors such as light quality ratio, light intensity, and light time. Since different plants have different requirements for light and different growth and development stages, it is necessary to carry out the best combination of light quality, light intensity, and light supplement time for the cultivated crops. Light quality ratio Compared with white light and single red and blue light, the combination of LED red and blue light shows comprehensive advantages for the growth and development of cucumber and cabbage seedlings. When the ratio of red and blue light is 8:2, the plant stem thickness, plant height, plant dry weight, fresh weight, strong seedling index, etc. are significantly increased, and it is also conducive to the formation of chloroplast matrix and basal lamella and the output of assimilation products. When the ratio of red and blue light is 8:1, cucumber seedlings have the highest plant height, stem thickness, leaf area, strong seedling index, aboveground and whole plant fresh quality, and the seedling leaves have higher POD and APX activities; Under the treatment with a blue light ratio of 6:3, the root vitality, leaf soluble protein, soluble sugar content and net photosynthetic rate of cucumber seedlings were the highest, and the SOD activity was relatively high.

Using a combination of red, green, and blue qualities for red bean sprouts is beneficial to its dry matter accumulation. Adding green light can promote the dry matter accumulation of red bean sprouts. The ratio of red, green, and blue light is 6:2:1. The growth is the most obvious. The red bean sprout hypocotyl elongation effect is the best under the treatment with the red and blue light ratio of 8:1, and the red bean sprout hypocotyl elongation is obviously inhibited under the treatment with the red and blue light ratio of 6:3, but the soluble protein content is the highest. When using the light with the ratio of red and blue light of 8:1 to the loofah seedlings, the seedling index of the loofah seedlings is the largest and the content of soluble sugar is the highest. When the light quality of the ratio of red and blue is 6:3, the chlorophyll-a The content, chlorophyll a/b ratio, and soluble protein content are the highest. Using a 3:1 ratio of red and blue light to celery can effectively promote the increase of celery plant height, petiole length, leaf number, dry matter quality, VC content, soluble protein content, and soluble sugar content; In cultivation, increasing the ratio of LED blue light promotes the formation of lycopene, free amino acids, and flavonoids, and increasing the ratio of red light promotes the formation of titratable acids; use light with a ratio of red and blue light to lettuce leaves at an 8:1 ratio At this time, it is conducive to the accumulation of carotenoids, and effectively reduces the content of nitrate and increases the content of VC.

Light intensity Plant growth under weak light is more susceptible to photoinhibition than under strong light. The net photosynthetic rate of tomato seedlings increased with the increase of light intensity [50, 150, 200, 300, 450, 550 μmol/(m2·s)], showing a trend of first increasing and then decreasing, and it was at 300 μmol/(m2·s). ) Reached the maximum; the plant height, leaf area, water content, and VC content of lettuce increased significantly under 150 μmol/(m2·s) light intensity treatment, and under 200 μmol/(m2·s) light intensity treatment The fresh weight, total weight, and free amino acid content of lettuce were significantly increased. Under 300 μmol/(m2·s) light intensity treatment, lettuce leaf area, water content, chlorophyll a, chlorophyll a+b, and chlorophyll a+b Carotene is reduced; compared with darkness, with the increase of LED supplementary light intensity [3, 9, 15 μmol/(m2·s)], the chlorophyll a, chlorophyll b, and chlorophyll-a of black bean sprouts The content of +b increased significantly. When the light intensity was 3 μmol/(m2·s), the content of VC was the highest, and the content of soluble protein, soluble sugar, and sucrose was the highest at 9 μmol/(m2·s)F; As the light intensity [(2~2.5)lx×103 lx, (4~4.5)lx×103 lx, (6~6.5)lx×103 lx] increases, the seedling time of pepper seedlings is shortened, and the soluble sugar content increases, but The content of chlorophyll a and carotenoids gradually decreased.

Illumination time Properly prolonging the illumination time can alleviate the low light stress caused by insufficient light intensity to a certain extent, help the accumulation of photosynthetic products of horticultural crops, and achieve the effect of increasing yield and improving quality. The VC content of sprouts showed a gradually increasing trend with the prolongation of light time (0, 4, 8, 12, 16, 20 h/day), while the free amino acid content, SOD, and CAT activities all showed a decreasing trend; With the prolongation of the light time (12, 15, 18 h), the fresh weight of the Chinese cabbage plant increased significantly; the VC content of Chinese cabbage leaves and stalks were the highest at 15 and 12 h; the soluble protein content of Chinese cabbage leaves gradually decreased. However, the stalk treatment was the highest at 15 h; the soluble sugar content of cabbage leaves gradually increased, while the stalk was the highest at 12 h. When the ratio of red and blue light is 1:2, compared with 12 h of light, the 20 h light treatment reduces the relative content of total phenols and flavonoids in green leaf lettuce, but when the ratio of red and blue light is 2:1 Under 20 h light treatment, the relative content of total phenols and flavonoids in green leaf lettuce was significantly increased.

From the above, it can be seen that different light formulas have different effects on photosynthesis, photomorphogenesis, and carbon, and nitrogen metabolism of different crop types. How to obtain the best light formula, light source configuration, and formulation of intelligent control strategies requires plant species as the starting point. , And appropriate adjustments should be made according to the commodity demand of horticultural crops, production goals, production factor conditions, etc., to achieve the goal of intelligent control of the light environment and high-quality and high-yield horticultural crops under energy-saving conditions.