In the heart of Shanghai, a team of researchers led by Zihan Wang from the College of Science at the Shanghai Institute of Technology has made a significant breakthrough in the realm of controlled-environment agriculture. Their work, recently published in Horticulturae (which translates to “Horticulture” in English), focuses on optimizing LED lighting for Italian lettuce cultivation in miniature plant factories. This research could have profound implications for the energy sector and vertical farming industries.
The study introduces a novel spectral-spatial co-optimization strategy for LED lighting, tailored to the specific physiological needs of Italian lettuce (Lactuca sativa L. var. italica). The team developed a miniature plant factory system, a compact space measuring 400 mm × 400 mm × 500 mm (L × W × H), where they tested seven customized spectral treatments using 2835-packaged LEDs. These treatments incorporated various combinations of blue and violet LED chips with precisely controlled concentrations of red phosphor.
One of the standout achievements of this research is the remarkable uniformity in spectral mixing and spatial light intensity. The spectral mixing uniformity exceeded 99%, while the spatial light intensity uniformity surpassed 90%. To tackle spatial light heterogeneity, the researchers employed a particle swarm optimization (PSO) algorithm to determine the optimal LED arrangement, boosting the photosynthetic photon flux density (PPFD) uniformity from 83% to 93%.
“The integration of spectral customization with algorithmically optimized spatial distribution is a game-changer,” said Wang. “It not only enhances crop yield but also significantly improves energy efficiency, which is crucial for the scalability and sustainability of vertical farming systems.”
The system operates with a fixture-level power consumption of only 75 W, making it highly energy-efficient. Experimental evaluations across seven treatment groups revealed 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, a 30% reduction in SPAD value (indicative of improved light-use efficiency), and significant improvements in plant morphological parameters.
“These results demonstrate that our approach is both effective and scalable,” Wang added. “It paves the way for more efficient and productive vertical farming systems, which can have a substantial impact on the energy sector and the broader agricultural industry.”
The research highlights the potential for integrating advanced lighting technologies with algorithmic optimization to create more sustainable and efficient farming practices. As the world grapples with the challenges of climate change and resource depletion, innovations like these offer a glimmer of hope for a more sustainable future.
This study, published in Horticulturae, not only advances our understanding of LED spectral customization and optimization but also sets a new standard for energy-efficient crop cultivation. The implications for the energy sector are vast, as the techniques developed by Wang and his team could be applied to a wide range of crops and farming systems, ultimately contributing to a more sustainable and resilient food supply chain.