Illumination screening and uniformity simulation of hydroponic lettuce in artificial light plant factory

Abstract

With the development of LED plant lighting technology and its wide application in agricultural production, LED plant grow lights have become the mainstream light source used for plant lighting in plant factories with artificial light (PFALs). Artificial plant light source is different from natural light source, its biggest characteristic in light quality, light intensity, photo period and light form all can be accurately and intelligently regulated, ideally can continue to provide plants with light energy at the lowest cost, guarantee annual production and supply with high quality and efficient agricultural products, for the different living environment of people continue to supply the essential fresh plant products. Illumination and illumination uniformity have a significant impact on plant photosynthesis and growth, and are also the basis of the design of plant lighting system in PFALs. In this paper, taking the lettuce varieties planted in the field as the test materials and experimental objects, we design the illumination gradient test, simulate the illumination uniformity of LED forms with different arrangement by using the computer simulation method, and study the influence of different illumination and LED arrangement forms on the growth and biomass of hydroponic Lettuce in PFALs, so as to provide the best lighting solution for the industrialization and standardized production of lettuce in plant factories. The results of the study showed that: for hydroponic lettuce in PFAL’s lighting environment, the illumination uniformity of matrix LED light source is the best. The optimal lighting distance is between about 25cm and 30 cm from the lettuce. A red-blue light mixture ratio of 7:1 is the best light quality ratio for lettuce during seedling stage, and a red-blue light mixture ratio of 6:1 is the best light quality ratio in the growth period. The optimum light intensity is 400 2 µmol m s / ⋅ . The best daily illumination time is 16 h d/ , and the illumination time can be appropriately extended to achieve the purpose of harvesting lettuce in advance.