What Are The Specific Spectral Ratios Of Far-red To Red Light That Would Optimize Phytochrome B-mediated Suppression Of Seedling De-etiolation In Arabidopsis Thaliana Under Controlled Environment Agriculture Conditions, And How Might These Ratios Be Modulated Using LED-based Supplemental Lighting To Enhance Crop Yields In Vertically-stacked Growing Systems?

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To address the question of optimizing phytochrome B-mediated suppression of seedling de-etiolation in Arabidopsis thaliana using LED-based supplemental lighting in vertical farming, the following approach is proposed:

Key Findings and Recommendations:

  1. Understanding Phytochrome B Role:

    • Phytochrome B is activated by red light (R, ~660 nm) and inactivated by far-red light (FR, ~730 nm). Active phytochrome B (Pfr) suppresses de-etiolation, keeping seedlings in a more etiolated state.

  2. Optimal Spectral Ratio:

    • To suppress de-etiolation, maintain higher levels of Pfr by using a higher red to far-red light ratio (R:FR). The optimal ratio is typically in the range of 2:1 to 4:1. This ratio ensures sufficient Pfr activity to inhibit de-etiolation effectively.

  3. LED Lighting Strategy:

    • Utilize LED grow lights with adjustable red and far-red diodes. Increase the intensity or number of red LEDs relative to far-red LEDs to achieve the desired R:FR ratio.
    • Example: Use a combination of 660nm red and 730nm far-red LEDs, adjusting their proportions to maintain a ratio of 3:1 or 4:1 during the seedling stage.

  4. Considerations for Vertical Farming:

    • In vertically-stacked systems, tailor lighting setups for each growth stage. Apply higher R:FR ratios during seedling stages to control de-etiolation, then adjust for subsequent growth phases as needed.
    • Be mindful of energy efficiency; ratios beyond the saturation point may not provide additional benefits.

  5. Practical Implementation:

    • Each growing layer in the vertical system can be equipped with LED modules that allow precise control over spectral output. This modular approach enables customization of light conditions for optimal growth across different stages.

By implementing these strategies, vertical farming operations can enhance crop yields through precise control of the light environment, leveraging the phytochrome B system to regulate seedling development effectively.