| The application of light-emitting diode (LED) in agriculture and bio-industry has been concerned by all over the world along with the development of LED technology. LED not only has many advantages, such as small size, long life, low energy consumption, securing wave length and low production of heat, but also can emit the exact spectrum based on the need of plant. LED can actualize a lot of functions, such as energy saving, environment protection and efficient space utilization, which can not be achieved by conventional light source.Light spectrum plays an important role in plant development, morphogenesis, metabolism and gene expression. Application of light spectrum of LED on plantlets are important for plant tissue culture, plant cultivation and bud seeding vegetable. In this thesis, Phalaenopsis and Oncidium of orchids, tomato and lettuce seedlings, pea and radish seeds were tested to investigate the effects of light spectrum on growth of plantlets in different stages. The results are as follows:1. Effects of light qualities on the growth and leaf ultrastructure chloroplast of tomato and lettuce seedlings were studied. The results showed that, under red LED, the soluble sugar, starch of tomato and lettuce seedlings were significantly higher than those of the control, starch granules swelled obviously. Under blue LED, the length of hypocotyl of tomato seedlings were remarkably restrained, the chlorophyll a and carotenoid content of leaf of both seedlings were significantly increased. Under red+blue LED, the soluble sugar, starch, sucrose and C/N of lettuce seedlings were maximal and significantly higher than those of the red LED, the length of main roots of both seedlings were significantly increased as well, and the leaf chloroplast morphology was normal, the number of grana increased, the stroma lamellae was clear, the starch granules were less than those of red LED. The results suggested that effects of light quality on the photomorphogenesis, growth, metabolism of carbon and nitrogen including development of leaf chloroplast of plant seedlings were remarkable. Photosynthate was accumulated significantly but its transport was hindered badly under red LED. Adding some blue LED to red LED was in favor of the accumulation of photosynthate, growth of roots and export of assimilation product of lettuce seedlings.2. The effects of different light spectral energy distribution of LED on proliferation and growth of chrysanthemum plantlets in vitro were studied. The results showed that, red LED was in favor of enhancing plant height and the third internode length, and synthesizing soluble sugar, starch and carbohydrate; the contents of chlorophyll b, chlorophyll a+b and carotenoid of shoots including contents of amino acid of plantlets in vitro were significantly increased by blue LED; complex of red, blue and yellow LED was not only suitable for differentiation and proliferation of shoots in vitro, but for pigment synthesis, growth and root vigor of plantlets in vitro. The results indicated that, as compared with fluorescent light, application of complex of red+blue+yellow LED was propitious to improve propagation coefficient, breed vigorous plantlets and decrease energy consumption.3. The effects of different light spectral energy distribution of light-emitting diode (LED) on proliferation and growth of Oncidium and Phalaenopsis plantlets in vitro were studied. The results showed that, red LED was in favor of enhancing plant height and synthesizing soluble sugar, starch and carbohydrate; the content of chlorophyll b, chlorophyll a+b and carotenoid of shoots including content of amino acid of plantlets in vitro were significantly increased by blue LED; complex of red, blue and yellow LED, Oncidium and Phalaenopsis plantlets all had strong growth, high enriched degree, more quantity roots and higher dry and fresh mass. The results indicated that, as compared with fluorescent light, application of complex of red+blue+yellow LED was propitious to improve propagation coefficient, breed vigorous plantlets and decrease energy consumption.4.Effects of different light qualities(red light, far-red light, yellow light, blue light, and red+blue light) generated from light emitting diodes (LED) on the growth of radish sprouting seedlings were studied. Fluorescent light was used as the control. From the experimental results, red LED was the most effective for the growth of radish sprouting seedlings, and exhibited the highest hypocotyl length, cotyledon area and fresh/dry weight. Red LED and red+blue LED significantly increased the content of soluble sugar and starch; far-red LED significantly increased the content of Zn, P, Mn, Mg, Ca and Na. The results suggested that application of red LED could accelerate the growth of the radish sprouting seedlings, increase the yield and improve some nutrient component. 5. Effects of different light qualities(red light, yellow light, blue light, and red+blue light) generated from light emitting diodes (LED) on the growth of pea seedlings were studied. Fluorescent light was used as the control. From the experimental results, yellow LED was the most effective for the growth of pea seedlings, and exhibited the highest hypocotyl length. Red LED is secondly, compared with yellow LED, the cotyledon area was higher. The cotyledon area was lowest under blue LED and yellow LED. Red LED plays an important role in hypocotyl elongation, cotyledon expansion, photosynthetic rate improvement and dry matter accumulation. Red+blue LED significantly increased the cotyledon area and the contents of chlorophyll; Blue LED had highest amino acid and protein content. The results suggested that application of LED could accelerate the growth of the radish sprouting seedlings, increase the yield and improve some nutrient component.In conclude, this study supported the feasibility of application of light spectrum regulation of LED on agriculture and bio-industry, which would replace fluorescent and be widely used in plant cultivation, plant tissue culture and bud seeding vegetable. |
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