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NEW RESEARCH! The role of red and white light in optimizing growth and accumulation of plant specialized metabolites at two light intensities in medical cannabis (Cannabis sativa L.)

The research was authored by Mexximiliaan M. S. F. Holweg, Elias Kaiser, Iris F. Kappers, Ep Heuvelink, and Leo F. M. Marcelis from the Horticulture and Product Physiology and Laboratory of Plant Physiology departments at Wageningen University in Wageningen, Netherlands.

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The role of red and white light in optimizing growth and accumulation of plant specialized
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Key Findings

The study investigated the effects of different light spectra and intensities on the growth and accumulation of specialized metabolites in medical cannabis. Key findings include:

  1. Inflorescence Weight:

  • White light with dual red peaks (640 and 660 nm) significantly increased inflorescence weight compared to white light with a single red peak (660 nm).

  • This increase was linked to higher overall plant dry matter production and a more open plant architecture, enhancing light capture.

  1. Light Use Efficiency:

  • At low light intensity (600 μmol m-2 s-1), dual red peaks improved photosynthetic efficiency and light use efficiency.

  • High light intensity (1200 μmol m-2 s-1) with dual red peaks increased terpenoid concentrations without affecting cannabinoid concentrations.

  1. Plant Morphology:

  • Increasing the white fraction of light led to compact plant architecture and improved dry matter partitioning to inflorescences.

  • Spectrum broadness did not significantly affect inflorescence weight or total plant dry matter production.

ROI for Cannabis Cultivators


  • Increased Yield: Using white light with dual red peaks can boost inflorescence weight, leading to higher yields per plant.

  • Improved Quality: Higher terpenoid concentrations at high light intensities can enhance the quality and medicinal value of cannabis.

  • Energy Efficiency: Optimizing light spectra can improve photosynthetic efficiency, reducing energy costs associated with lighting in controlled environments.


  • Initial Investment: Implementing advanced LED lighting systems with customizable spectra may require significant upfront costs.

  • Operational Adjustments: Adjusting light spectra and intensities might necessitate changes in cultivation practices and monitoring.

Return on Investment:

  • Higher Revenue: Increased yield and quality can lead to higher market prices and sales.

  • Energy Savings: Improved light use efficiency can reduce electricity consumption, lowering operational costs over time.

Implementation Steps for Cultivators

  1. Evaluate Current Lighting Systems:

  • Assess the current lighting setup to determine potential areas for improvement.

  • Consider transitioning to LED systems if not already in use.

  1. Select Optimal Light Spectrum:

  • Implement white light with dual red peaks (640 and 660 nm) for both low and high light intensities.

  • Increase the white fraction of light to enhance plant architecture and dry matter partitioning.

  1. Adjust Light Intensity:

  • Set light intensity to 600 μmol m-2 s-1 during the vegetative phase and increase to 1200 μmol m-2 s-1 during the flowering phase for optimal results.

  1. Monitor and Optimize:

  • Regularly monitor plant responses to the new lighting conditions.

  • Adjust other environmental factors (e.g., temperature, humidity, CO2 levels) to complement the lighting adjustments.

  1. Training and Education:

  • Train cultivation staff on the new lighting system and its benefits.

  • Stay updated with the latest research and advancements in horticultural lighting.

By implementing these steps, cannabis cultivators can optimize plant growth and metabolite accumulation, ultimately enhancing both yield and quality while improving energy efficiency.

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