The regulation of light on plant growth and development includes seed germination, stem elongation, leaf and root development, phototropism, chlorophyll synthesis and decomposition, and flower induction. The lighting environment elements in the facility include light intensity, illumination period and spectral distribution. The artificial fill light can be used to adjust its elements without being restricted by weather conditions.
Plants have selective absorption of light, and light signals are perceived by different photo receptors. At present, there are at least three types of photo receptors in plants, photo sensitins (absorbing red and far red light), and cryptochrome (absorbing blue light and Near ultraviolet light) and ultraviolet light receptors (UV-A and UV-B). Using a specific wavelength light source to illuminate the crop can increase the photosynthesis efficiency of the plant and accelerate the formation of the light form, thereby promoting the growth and development of the plant. Plant photosynthesis mainly uses red orange light (610 ~ 720 nm) and blue purple light (400 ~ 510 nm). Using LED technology, it is possible to emit monochromatic light (such as red light with a peak of 660 nm and blue light with a peak of 450 nm) in accordance with the wavelength band of the strongest absorption region of chlorophyll, and the spectral domain width is only ±20 nm. At present, it is believed that red orange light will accelerate the development of plants, promote the accumulation of dry matter, the formation of bulbs, roots, leaf balls and other plant organs, causing plants to flower and firm earlier, and play a leading role in plant color enhancement; Blue and violet can control the leaf light of plants, promote stomatal opening and chloroplast movement, inhibit stem elongation, prevent plant growth, delay plant flowering and promote vegetative growth; red and blue LEDs can make up for both monochrome The lack of light forms a spectral absorption peak that is basically consistent with crop photosynthesis and morphogenesis, and the light energy utilization rate can reach 80% to 90%, and the energy saving effect is remarkable.
The installation of LED fill light in the facility gardening can achieve a very significant increase in production. Studies have shown that 300 μmol/(m2·s) LED strips and LED tubes 12h (8:00～20:00) fill the number of cherry tomatoes, total yield and single fruit weight are significantly improved, of which LED The lamp fill light increased by 42.67%, 66.89% and 16.97%, respectively, and the LED lamp fill light increased by 48.91%, 94.86% and 30.86% respectively. The total growth period of LED light fill light [red and blue light ratio of 3:2, light intensity of 300 μmol / (m2 · s)] treatment can significantly increase the single fruit quality and unit area yield of melon and eggplant, the melon increased by 5 .3%, 15.6%, eggplant increased by 7.6%, 7.8%. Through the whole growth period LED light quality and its intensity and duration of air conditioning, it can shorten the plant growth cycle, improve the commercial yield, nutritional quality and form value of agricultural products, and achieve high efficiency, energy saving and intelligent production of facility horticultural crops.