The light quality is modulated by the accurate spectrum principle of the new light source of the LED plant growth lamp, and the tomatoes in the facility are regularly supplemented with light, and the effect of different light quality in the LED plant supplement light on the growth of vegetable seedlings is studied. The actual results showed that LED red light and red and blue light had significant effects on tomato seedling growth indicators, and the stem thickness, fresh dry weight and strong seedling index were significantly higher than those of tomatoes without supplemental light treatment. Red light or yellow light significantly increases the chlorophyll and carotenoid content of Israeli Hongfeng tomatoes; red light or red blue light significantly increases the soluble sugar content of tomatoes. Therefore, supplementing red light or red and blue light in the seedling stage can promote the growth of tomato seedlings and is beneficial to the cultivation of strong seedlings, but it needs to be based on reasonable light supplementation strategies and benchmarks.
In most areas of facility cultivation, vegetable seedlings in winter and spring are under low temperature and weak light. Some cold-proof and thermal insulation measures have reduced the light intensity, changed the light intensity, affected the healthy growth of seedlings, and directly affected the yield and quality of the product. LED plant lights have outstanding advantages such as pure light quality, high light efficiency, rich wavelength types, convenient spectral energy modulation, and environmental protection and energy saving. It is a new type of LED light source that replaces fluorescent lamps and is used for plant cultivation. In recent years, the application of environmentally friendly and energy-saving plant LED lights to the light environment control technology to promote plant growth and development has gradually attracted attention. Foreign scholars have found through research that monochromatic LED or combined LED light quality regulation has different effects on the morphogenesis and photosynthesis of spinach, radish, lettuce, sugar beet, pepper, perilla and other plants, which can improve photosynthetic efficiency and promote growth. And the purpose of regulating morphology. Some domestic scholars have studied the effect of LED light quality on the growth of cucumbers, tomatoes, colorful sweet peppers, strawberries, rapeseed and other plants, and confirmed the special effects of light quality on the growth of plant seedlings, but because the experiments mostly use ordinary electric light sources or light filters, etc. Measures can be used to obtain light quality, and it is impossible to quantitatively and accurately modulate the spectral energy distribution.
Tomato is an important vegetable type in my country’s plant cultivation. Changes in the light environment in the facility have a great impact on the growth and development of their seedlings. The use of LEDs to accurately control light quality and light quantity, and compare the effects of different light quality supplementary light on the growth of tomato seedlings, aims to provide help for the reasonable regulation of the light environment of vegetable facilities.
The experimental materials were two varieties of tomato “Dutch Red Powder” and “Israel Hongfeng”.
Each treatment is equipped with 6 LED plant growth lights, and a reflective film is installed between each treatment for isolation. Supplement light for 4 hours every day, the time is 6:00-8: 00 and 16: 00-18: 00. Adjust the distance between the LED light and the plant so that the vertical height of the light from the ground is 50 to 70 cm. The plant height and root length were measured with a ruler, the stem thickness was measured with a vernier caliper, and the stem thickness was measured at the stem base. During the determination, random sampling was adopted for the samples of seedling plants of various varieties, with 10 plants drawn each time. The healthy seedling index was calculated according to the method of Zhang Zhenxian et al. (Strong seedling index=stem thickness/plant height×whole plant dry mass); chlorophyll was determined by extraction with 80% acetone; root vigor was determined by TYC method; soluble sugar content was determined by anthrone colorimetry Determination.
results and analysis
The effect of different light quality on the morphological indexes of tomato seedlings, except for green light, the strong seedling index of tomato “Israel Hongfeng” seedlings was significantly higher than that of the control, the order was red and blue light>red light>yellow light>blue light; all light quality treatments The fresh and dry weight indicators of the control were significantly higher than those of the control, and the red and blue light treatments reached a larger value; except for the green light and blue light, the stem thickness of the other light quality treatments were significantly higher than that of the control, followed by red light>red and blue light>yellow Light.
Tomato “Dutch Red Powder” reacts slightly differently to light quality treatment. Except for the green light, the healthy seedling index of tomato “Dutch Red Powder” seedlings was significantly higher than that of the control, followed by blue light>red blue light>red light>yellow light; the fresh and dry weight indexes of all light quality treatments were significantly higher than those of the control. The red light treatment reached a larger value; the stem thickness of all light quality treatments was significantly higher than that of the control, and the order was red light>yellow light>red and blue light>green light>blue light. Comprehensive analysis of various indicators, the supplement of red, blue and red light has significant effects on the growth of the two tomato varieties. The stem thickness, freshness, dry weight and strong seedling index are significantly higher than those of the control. But there are slight differences between varieties. Tomato “Israel Hongfeng” under the red and blue light treatments, its fresh weight, dry weight and strong seedling index all reached large values, and there were significant differences with other treatments; tomato “Dutch Red Powder” under the red light treatment. Its plant height, stem thickness, root length, fresh weight, and dry weight all reached larger values, and there were significant differences with other treatments.
Under red light, the plant height of tomato seedlings was significantly higher than that of the control. Red light plays an important role in promoting stem elongation, increased photosynthesis rate and dry matter accumulation. In addition, supplementing red light can also significantly increase the root length of tomato “Dutch red powder”, which is similar to the study on cucumbers, indicating that red light can also promote The role of hair roots. Under the supplement of red and blue light, the strong seedling index of the three vegetable seedlings was significantly higher than that of the control.
The combination of red and blue LED spectrum has a positive impact on the growth and development of plants, which is better than monochromatic light treatment. The effect of red LED on the growth of spinach is not obvious, and the growth morphology index of spinach is significantly improved after adding blue LED. The bioaccumulation of sugar beet grown under the combined light of the red and blue LED spectrum is large, the betain accumulation in the hair root is significant, and a higher sugar and starch accumulation are produced in the hair root. Some studies believe that the combination of red and blue LED lights can increase the net photosynthetic rate to improve plant growth and development because the spectral energy distribution of red and blue light is consistent with the chlorophyll absorption spectrum. In addition, supplementation of blue light has positive effects on the fresh weight, dry weight and strong seedling index of tomato seedlings. Blue light irradiation at the seedling stage can also promote the growth of tomato seedlings, which is conducive to the cultivation of strong seedlings. This study also found that supplementing with yellow light significantly increased the chlorophyll and carotenoids content of tomato “Israel Hongfeng”. The results of the study showed that green light promotes the rapid growth of Arabidopsis chlorosis seedlings, and it is believed that a new light signal activated by green light promotes stem elongation and antagonizes growth inhibition.
The many conclusions obtained in this experiment are similar or the same as those of the predecessors, confirming the special status of LED spectrum in plant growth. The effect of light quality on the nutritional morphogenesis and physiological characteristics of plant seedlings is significant, which is important for production. Use supplementary light quality to cultivate strong seedlings to provide theoretical basis and feasible technical parameters. However, LED supplementary light is still a very complicated process. In the future, it is necessary to systematically explore the effects and mechanisms of light environmental factors such as different spectrum (light quality) energy (light quantum density) distribution and photoperiod on the growth of plant seedlings, so as to cultivate seedlings for factory facilities. Reasonable regulation of Zhongguang environment provides benchmarks.

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Post time: Jul-28-2020