Horticultural Lighting
Lighting designed for every space
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Technical Horticulture Lighting: Spectrum Engineering and Crop Optimisation
Technical horticulture lighting represents a paradigm shift in lighting engineering, where the metric is no longer human visual perception (lumens) but the interaction of photons with plant photoreceptors. A high-performance horticultural lighting project is based on delivering the Photosynthetically Active Radiation (PAR) required to maximise the photosynthetic rate, control plant morphology and optimise production in controlled-environment agriculture (CEA), greenhouses and vertical farming.
Fundamental Metrics in Photobiological Lighting
To assess the performance of a horticultural lighting system, it is essential to use measurement units specific to plant physiology:
- PPF (Photosynthetic Photon Flux): Measures the total quantity of photons emitted by the luminaire per second within the PAR range (400-700 nm), expressed in μmol/s.
- PPFD (Photosynthetic Photon Flux Density): Indicates the quantity of photons that actually reach the plant canopy per square metre per second (μmol/m²/s). It is the critical parameter for determining uniformity and intensity at the cultivation plane.
- Photosynthetic Photon Efficacy (μmol/J): The energy efficiency metric of the system, indicating how many micromoles of photons the luminaire produces per joule of energy consumed. Our high-end solutions reach efficiencies of up to 2.9 - 3.5 μmol/J.
Designing Light Recipes
The light spectrum directly influences plant development through photoreceptors such as chlorophylls, phytochromes and cryptochromes. We tailor the spectral composition to the phenological phase:
- Blue Spectrum (400-500 nm): Fundamental for the vegetative phase. Promotes compact plants, robust stems and foliar development, inhibiting excessive elongation.
- Red Spectrum (600-700 nm): The most efficient wavelength for photosynthesis. A peak at 660 nm (Deep Red) is essential to maximise biomass and enhance flowering.
- Far-Red (730 nm): Although outside the traditional PAR range, its inclusion is vital for the Emerson Effect, accelerating the transition to flowering and improving fruit size.
- Full Spectrum (White Light): Provides a continuous spectrum that facilitates visual inspection of pests and diseases by the operator, offering a balanced solution for the entire life cycle.
Spectrum Comparison by Phenological Phase
| Cultivation Phase | Predominant Spectrum | Biological Objective | Suggested PPFD (μmol/m²/s) |
|---|---|---|---|
| Propagation / Clones | Blue / Cool White | Root development | 50 - 150 |
| Vegetative | Full Spectrum (Blue/Red) | Structure and vigour | 300 - 600 |
| Flowering / Production | Intense Red / Far-Red | Maximisation of biomass | 600 - 1000+ |
Construction Engineering and Thermal Management
Cultivation environments present extreme conditions such as high relative humidity and fluctuating temperatures:
- IP65/IP66 Protection: Luminaires must be fully sealed to withstand spray, fogging and chemical cleaning processes.
- Passive Heat Dissipation: The use of oversized extruded aluminium bodies removes the need for active fans, reducing failure points and avoiding thermal stress on plant tips (heat burns).
- DLI (Daily Light Integral) Management: Integration with control systems to calculate the total quantity of photons delivered over 24 hours, adjusting intensity according to natural sunlight available in greenhouses to save energy.
Frequently Asked Questions (FAQs) on Horticultural Lighting
Why shouldn't lumens or lux be used to measure light for plants?
Lumens are weighted by the human eye sensitivity curve, which is greatest in the green-yellow spectrum. Plants have a different sensitivity, focused mainly on the blue and red spectra. Therefore, a luminaire with many lumens may be inefficient for plant growth if it does not emit photons at the appropriate wavelengths.
What is the "Emerson Effect" and how does it benefit production?
It is the increase in photosynthetic rate that occurs when plants are simultaneously exposed to wavelengths of 660 nm (red) and 730 nm (far-red). The combination of both makes the two photosystems (PSI and PSII) work in synergy, resulting in greater metabolic efficiency than the sum of both separately.
How does LED thermal management influence crop quality?
Unlike sodium lamps (HPS), LED does not emit radiant heat towards the plant. This allows the light source to be brought closer to the canopy without the risk of thermal stress, which increases light penetration into the lower parts of the crop and enables the use of multi-tier vertical farming systems.