| With the advantages of high-efficiency luminescence,good monochromaticity,easy combination,and low heat generation,etc,LED light source has become the first choice for plant light sources in modern agriculture.Light quality determines the growth efficiency of plants,and the core of agricultural light supplement is also the ratio of light quality.In this regard,this thesis uses LED as light source of plants,researching on the influences of different light qualities on the growth of glass lettuces and the optimization design of high-efficiency LED light array,and then provides certain scientific theoretical supports for the field of plant lighting.In this thesis,LEDs are used as the light source for plant growth,in order to study the influences of ratios of different light qualities on the growth of glass lettuces,green light is added to the LED red and blue composite light,and the light environment is constructed in the plant factory for hydroponic planting,and the green light with a gradient of PPFD is designed.The light processing group subsequently used n-person cooperation strategies and Shapley Value to design light quality contribution distribution experiments and conduct contribution distribution,mainly using LSD test and the DUCAN test for significance analysis of data.The research results show that green light can promote the growth and development of glass lettuces in a certain extent,and the best PPFD of green light is around48μmol/m~2/s.When the PPFD of R/G/B is 4/1/1,it is the best combination in the experiment that the growth indexes of glass lettuces(plant height,leaf area and fresh weight of the above-ground part,etc.)and the accumulation of physiological indexes(soluble protein,soluble sugar and chlorophyll)are the most beneficial with the addition of green light.In terms of the fresh material quality of the above-ground part of glass lettuces,the contribution ratio of RGB in the best combination is about 6/1/3.When the uniformity of PPFD or uniformity of illumination on the planting plane is above 80%,the growth uniformity of glass lettuce can reach more than 90%.In addition,in order to improve the light uniformity of the LED light array,orthogonal design and GA were used to design and optimize the RBG LED light array of plants in 2D and 3D,and ANOVA was used to obtain the contribution of optimal distribution of light of related factors.Finally,experiments are conducted to verify the best combination of parameters in this experiment.The results show that when the area of the source panel is 14cm×14 cm,the area of the target panel is 10 cm×10 cm,and the chips’combination is6R&6B&6G,a parameter combination in which all the chip positon distributions are designed by GA(genetic algorithm)is the best one for this experimnet.In addition,based on the data analysis of the ANOVA,the area of target panel plays a key role in the light optimization of plant light source,accounting for about 80%;The second is the area of light source panel with about 14%contribution.In the light experiment,the illumination uniformity of RBG chips are more than 86%.The error between them and the simulation is less than 5%,which is relatively consistent.This can meet the inherent demand for the unity of growth of plants.And then,starting with the theory of plants optics,we select three light components of RGB for the LED arrays designed.Quantum theory of light is used for the whole analysis by building a mathematical expression of the PPFD distribution and creating an evaluation function of photons’distribution,to determine the combination of optimal photons of LED arrays and optical experiment with best combination.Orthogonal experimental design is applied to complete the trial design with the four controlling factors selected due to their possibilities of influencing photon-uniformity.On the one hand,programming provides a suitable computing environment to operate the mathematical modeling and simulation,from which the best parameter combination can be found.On the other hand,the influential intensity of the controlling factors on the first-rank photons region is obtained by ANOVA.The experimental results show that the 2.5 cm interval among LED chips and staggered arrangement of R-G-B chips are conducive to the best combination.In addition,the angle of outward stretch of the chips substrate which is 0°and the vertical distance between the chip panel and the illumination plane which is 12 cm.The angle of outward stretch of chip’s substrate has the greatest influence on the distribution of optimal photons,closing to 50%.It is noteworthy that the influential ratio of chips’distribution is around 33%.The optical experiment results show that the PPFD uniformity of the optimal combination of the optical array and the simulation model is relatively consistent,and the uniformity of RGB is about80%.The lamp can initially meet the demand for uniform growth of plants,and provide some theoretical basis for building light environment for indoor agriculture. |
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