Optimizing LED lighting spectra for enhanced growth in controlled-environment vertical farms.

Area of Science:

• Horticulture
• Plant Physiology
• Sustainable Agriculture

Background:

• Controlled-environment vertical farms (CEVFs) offer urban food production solutions.
• High energy consumption, particularly from artificial lighting, is a major challenge for CEVFs.
• Optimizing light spectra can improve energy efficiency and crop yield.

Purpose of the Study:

• To optimize white LED lighting in CEVFs by supplementing with deep red (DR) and far-red (FR) light.
• To evaluate the effects of supplemental DR and FR light on lettuce and basil growth.
• To assess the impact of light intensity on plant biomass and quality.

Main Methods:

• Lettuce and basil were grown under five different LED lighting treatments.
• Treatments included a white LED base spectrum with varying levels of supplemental DR (660 nm) and FR (730 nm) light.
• One treatment featured doubled photosynthetic photon flux density (PPFD) to 244 µmol·m⁻²·s⁻¹, while others remained at 122 µmol·m⁻²·s⁻¹.

Main Results:

• Doubling PPFD significantly increased biomass, with 76% higher fresh weight in lettuce and 79% in basil compared to white light alone.
• Supplemental FR light increased leaf number and canopy size at equal PPFD.
• Supplemental DR light enhanced biomass accumulation, while white-only light maximized chlorophyll and nitrogen content.

Conclusions:

• Targeted supplementation with DR and FR light can improve light-use efficiency in CEVFs.
• Adjusting light spectra and intensity offers a strategy to enhance crop production in vertical farms.
• Further research into specific DR and FR ratios can optimize plant growth and quality.