The effect of LED lights on the growth of horticultural crops

The regulation of light on plant growth and development includes seed germination, stem elongation, leaf and root development, phototropism, synthesis and decomposition of chlorophyll, and flower induction. The lighting environment elements in the facility include the light intensity, light cycle, and spectral distribution. The use of artificial light can adjust the elements without being limited by the weather conditions.

The selective absorption of light by plants, and the perception of light signals by different photoreceptors, it has been found that there are at least three types of photoreceptors in plants, photofrin (absorbing red light and far-red light), cryptochrome (absorbing blue light and Near-ultraviolet light) and ultraviolet light receptors (UV-A and UV-B). The use of a specific wavelength light source to illuminate the crop can increase the photosynthesis efficiency of the plant and accelerate its photomorphogenesis, thereby promoting the growth and development of the plant. Photosynthesis of plants mainly utilizes red orange light (610~720 nm) and blue violet light (400~510 nm). Using LED technology, it is possible to radiate monochromatic light (e.g., red light with a peak at 660 nm, blue light with a peak at 450 nm) that conforms to the wavelength band of the strongest absorption region of chlorophyll, and the spectral domain is only ±20 nm wide. It is currently believed that red orange light will significantly accelerate the development of plants, promote the accumulation of dry matter, and the formation of bulbs, tuberous roots, leaf spheres, and other plant organs will cause early flowering and fruiting of plants and play a leading role in plant coloration. Blue and purple light can control the phototropism of plant leaves, promote stomatal opening and chloroplast movement, inhibit stem elongation, prevent plant growth, delay plant flowering and promote the growth of vegetative organs; red-blue LED combination can make up for both monochrome The deficiency of light forms the spectral absorption peak that is basically consistent with the crop photosynthesis and morphogenesis, and the light energy utilization rate can reach 80% to 90%, and the energy saving effect is significant.

The use of LED fill lights in facility gardening can achieve a very significant increase in production. Studies have shown that the number of fruits, total yield, and fruit weight of cherry tomatoes under LED strips and LED lamps 12h (8:00~20:00)lighting are significantly increased. LED lights with fill light increased by 42.67%, 66.89% and 16.97%, respectively, LED lamp fill light increased by 48.91%, 94.86% and 30.86%. The whole growth period LED light supplement [3:2 red-blue mass ratio, light intensity can significantly increase the fruit quality and yield per unit area of ??melon and eggplant. 5.3%, 15.6%, eggplant increased 7.6%, 7.8%. Through the whole growth period LED light quality and intensity, duration of air-conditioning, can shorten the growth cycle of plants, improve agricultural products, commercial production, nutritional quality and form value, to achieve efficient garden facilities, energy saving and intelligent production.