Bromeliad under LED: red/blue already offers perspective in main varieties

23 December 2020

Bromeliad is a tropical crop that’s grown in the Netherlands at relatively low temperature (21˚C in winter), receiving supplemental lighting with only ±40 µmol/m²/s SON-T. A recent study has shown that more light provides significantly more growth, while a higher temperature hardly has an effect. Doubling the intensity of the lighting hardly has an impact on electricity cost with LED.

Horti LED grow light

The goal of this research project was to study the effect of the light spectrum on growth and development of the varieties Guzmania ‘Ostara’, Tillandsia ‘Antonio’, Vriesea ‘Evita’ and Vriesea multiflower ‘Astrid’. The result provides guidelines when choosing the most efficient light spectrum for sustainable and year-round highly productive bromeliad cultivation.

Bromeliad plant response tests on various full LED light spectra.

Trial setup

To answer the research question, a cultivation trial was set up with four different spectra of supplemental lighting. The four bromeliad varieties were grown during 30 weeks (from potting to auction-ready) in eight climate cells at 22°C, 800 ppm CO₂, 80% relative humidity and 80 µmol/m²/s artificial sunlight (08:00-16:00). In addition to this winter light, supplemental lighting was applied for sixteen hours a day, with 80 µmol of the following spectra: sunlight, broadband LED (red/white/blue/far red), LED red/blue/far red and LED red/blue. Of all sixteen treatments (four varieties * four light spectra), the fresh and dry weight, number of leaves and leaf area were measured. At the final harvest, additional measurements were carried out to analyse the overall plant quality and plant shape.

Results and conclusions

All varieties were expected to develop and grow just fine under the sunlight spectrum, possibly less well under the other light spectra. But for Guzmania ‘Ostara’, Vriesea ‘Evita’ and Vriesea multiflower ‘Astrid’, even the simplest LED spectrum already turned out to be sufficient, namely LED red/blue. There were no differences in growth and development of these varieties under the different spectra. However, Tillandsia ‘Antonio’ didn’t perform well under any of the tested treatments. The leaves displayed white spots. The cause is not clear yet, but what was noticeable was that the leaf quality under sunlight was best, and worst under LED red/blue.

What this means for bromeliad growers in practice is that the lighting needs can apparently be met with LED red/blue. After all, together Guzmania and Vriesea represent the largest acreage (80 to 90%) in bromeliad cultivation. For practical purposes, adding a small amount of white LED light is recommended. How other varieties and cultivars respond cannot be concluded from this study, except that Tillandsia ‘Antonio’ didn’t develop well under lighting. Therefore it is recommended to screen all varieties and cultivars to be grown in winter on physiological problems under LED lighting.

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