Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories
Optimizing artificial lighting in controlled-environment agriculture is crucial for enhancing crop productivity and resource efficiency. This study presents a spectral–spatial co-optimization strategy for LED lighting tailored to the physiological needs of Italian lettuce (<i>Lactuca sativa<...
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2025-07-01
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| Series: | Horticulturae |
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| Online Access: | https://www.mdpi.com/2311-7524/11/7/779 |
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| author | Zihan Wang Haitong Huang Mingming Shi Yuheng Xiong Jiang Wang Yilin Wang Jun Zou |
| author_facet | Zihan Wang Haitong Huang Mingming Shi Yuheng Xiong Jiang Wang Yilin Wang Jun Zou |
| author_sort | Zihan Wang |
| collection | DOAJ |
| description | Optimizing artificial lighting in controlled-environment agriculture is crucial for enhancing crop productivity and resource efficiency. This study presents a spectral–spatial co-optimization strategy for LED lighting tailored to the physiological needs of Italian lettuce (<i>Lactuca sativa</i> L. var. italica). A miniature plant factory system was developed with dimensions of 400 mm × 400 mm × 500 mm (L × W × H). Seven customized spectral treatments were created using 2835-packaged LEDs, incorporating various combinations of blue and violet LED chips with precisely controlled concentrations of red phosphor. The spectral configurations were aligned with the measured absorption peaks of Italian lettuce (450–470 nm and 640–670 nm), achieving a spectral mixing uniformity exceeding 99%, while the spatial light intensity uniformity surpassed 90%. To address spatial light heterogeneity, a particle swarm optimization (PSO) algorithm was employed to determine the optimal LED arrangement, which increased the photosynthetic photon flux density (PPFD) uniformity from 83% to 93%. The system operates with a fixture-level power consumption of only 75 W. Experimental evaluations across seven treatment groups demonstrated that the E-spectrum group—comprising two violet chips, one blue chip, and 0.21 g of red phosphor—achieved the highest agronomic performance. Compared to the A-spectrum group (three blue chips and 0.19 g of red phosphor), the E-spectrum group resulted in a 25% increase in fresh weight (90.0 g vs. 72.0 g), a 30% reduction in SPAD value (indicative of improved light-use efficiency), and compared with Group A, Group E exhibited significant improvements in plant morphological parameters, including a 7.05% increase in plant height (15.63 cm vs. 14.60 cm), a 25.64% increase in leaf width (6.37 cm vs. 5.07 cm), and a 6.35% increase in leaf length (10.22 cm vs. 9.61 cm). Furthermore, energy consumption was reduced from 9.2 kWh (Group A) to 7.3 kWh (Group E). These results demonstrate that integrating spectral customization with algorithmically optimized spatial distribution is an effective and scalable approach for enhancing both crop yield and energy efficiency in vertical farming systems. |
| format | Article |
| id | doaj-art-af43186700964f8fa07fc35ebdd71ebd |
| institution | Kabale University |
| issn | 2311-7524 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Horticulturae |
| spelling | doaj-art-af43186700964f8fa07fc35ebdd71ebd2025-08-20T03:36:14ZengMDPI AGHorticulturae2311-75242025-07-0111777910.3390/horticulturae11070779Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant FactoriesZihan Wang0Haitong Huang1Mingming Shi2Yuheng Xiong3Jiang Wang4Yilin Wang5Jun Zou6College of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaCollege of Science, Shanghai Institute of Technology, No. 100, Haiquan Road, Fengxian District, Shanghai 201418, ChinaOptimizing artificial lighting in controlled-environment agriculture is crucial for enhancing crop productivity and resource efficiency. This study presents a spectral–spatial co-optimization strategy for LED lighting tailored to the physiological needs of Italian lettuce (<i>Lactuca sativa</i> L. var. italica). A miniature plant factory system was developed with dimensions of 400 mm × 400 mm × 500 mm (L × W × H). Seven customized spectral treatments were created using 2835-packaged LEDs, incorporating various combinations of blue and violet LED chips with precisely controlled concentrations of red phosphor. The spectral configurations were aligned with the measured absorption peaks of Italian lettuce (450–470 nm and 640–670 nm), achieving a spectral mixing uniformity exceeding 99%, while the spatial light intensity uniformity surpassed 90%. To address spatial light heterogeneity, a particle swarm optimization (PSO) algorithm was employed to determine the optimal LED arrangement, which increased the photosynthetic photon flux density (PPFD) uniformity from 83% to 93%. The system operates with a fixture-level power consumption of only 75 W. Experimental evaluations across seven treatment groups demonstrated that the E-spectrum group—comprising two violet chips, one blue chip, and 0.21 g of red phosphor—achieved the highest agronomic performance. Compared to the A-spectrum group (three blue chips and 0.19 g of red phosphor), the E-spectrum group resulted in a 25% increase in fresh weight (90.0 g vs. 72.0 g), a 30% reduction in SPAD value (indicative of improved light-use efficiency), and compared with Group A, Group E exhibited significant improvements in plant morphological parameters, including a 7.05% increase in plant height (15.63 cm vs. 14.60 cm), a 25.64% increase in leaf width (6.37 cm vs. 5.07 cm), and a 6.35% increase in leaf length (10.22 cm vs. 9.61 cm). Furthermore, energy consumption was reduced from 9.2 kWh (Group A) to 7.3 kWh (Group E). These results demonstrate that integrating spectral customization with algorithmically optimized spatial distribution is an effective and scalable approach for enhancing both crop yield and energy efficiency in vertical farming systems.https://www.mdpi.com/2311-7524/11/7/779LED spectral customizationminiature plant factoryPSO optimizationPPFD uniformityenergy efficiencyabsorption-guided lighting design |
| spellingShingle | Zihan Wang Haitong Huang Mingming Shi Yuheng Xiong Jiang Wang Yilin Wang Jun Zou Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories Horticulturae LED spectral customization miniature plant factory PSO optimization PPFD uniformity energy efficiency absorption-guided lighting design |
| title | Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories |
| title_full | Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories |
| title_fullStr | Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories |
| title_full_unstemmed | Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories |
| title_short | Optimized Spectral and Spatial Design of High-Uniformity and Energy-Efficient LED Lighting for Italian Lettuce Cultivation in Miniature Plant Factories |
| title_sort | optimized spectral and spatial design of high uniformity and energy efficient led lighting for italian lettuce cultivation in miniature plant factories |
| topic | LED spectral customization miniature plant factory PSO optimization PPFD uniformity energy efficiency absorption-guided lighting design |
| url | https://www.mdpi.com/2311-7524/11/7/779 |
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