| Light,as an external environmental impact factor,is necessary for plant growth and morphogenesis.It regulates plant growth and morphogenesis mainly from the aspects of photoperiod,light intensity and light quality.Light quality,the wavelength of light,is an important property of light.The spectral wavelength of visible light is 380-780nm,while the main absorption spectrum of plants is mainly in the red light area?640-660nm?and the blue light area?430-450nm?.As we know,the composition of visible light spectrum in the plant leaf surface will change with the change of weather and climate in the nature environment.Therefore,the artificial light source can be used to supplement the light source to plants at the necessary time.In modern facility agriculture,artificial lights has also been widely used to supplement the necessary light sources for crops to increase their output.With the development of semiconductor lighting technology,LED has become the first choice of plant light source in facility agriculture because of its advantages of high photoelectric conversion efficiency,low energy consumption,single wavelength,cold light source and so on.In this paper,we studied from two aspects.On the one hand,LED was used as the supplement light source to study on the light environment requirement of plant growth.On the other hand,we designed the LED array to improve the efficiency for LED plant lamps based on the properties of plant growth.In this paper,LED was used as the supplement light source to study on the effect of different light quality on the growth of cabbage and aloe.The results show that the red light can promote the elongation of aloe leaves,the blue light is beneficial to increase thickness of the aloe leaf,and the light quality?R/B=7/1?has the greatest increase in each index of aloe,which has the greatest influence on the growth of aloe.The white light and combination light quality?R/B=3/1?is beneficial to the growth of cabbage when the light treatment PPFD is85?mol·m-1·s-2.However,the addition of yellow light on the basis of the mixed light quality?R/B=3/1?is not conducive to the growth of cabbage.In this paper,we designed and optimized the LED array to improve the effective utilization of LED plant lamps based on Taguchi experimental method.Then the ANOVA method was used to study on the which factor had the lagest influence on R/B distribution at10 centimeters'plane.The study shows that the optimal combination consisted by the arrangement of blue LED chip on the center and red LED chip on the ring,which based on curvature radius of 50mm concave surface,the LED numbers consisted by six red LED chips and one blue LED chip,and the LED chips distance of 10mm.And the distance between the LED chips had the greatest impact on the distribution of R/B,accounting for 35.17%.Of course,the arrangement of LED chips can not be ignored,because it occupies 28.05%of the impact of the ratio.Then,we combined the genetic algorithm with the Taguchi method to design the LED array to improve the effective utilization of LED plant lamps.The ANOVA method also was used to study on the which factor had the lagest influence on R/B distribution at 10centimeters'plane.The results show that when the number of LED chips is 12,the distance between source panel and target panel is 150mm,the area of target panel is 30mm*30mm,the area of source panel is 50mm*50mm,the illumination uniformity is the optimized.Through the ANOVA,we can know the distance of target panel and source panel has the greatest impact on the uniform distribution,occupying 81.29%of the proportion.These studies will provide a theoretical basis for further optimization of LED plant light source. |
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