Three worlds came together at the High Tech Campus in Eindhoven for Lux’s Horticultural Lighting Conference. Speakers from the commercial growing community, plant research scientists and the LED industry offered their views on the future of lighting technology for crops grown intensively indoors. Inevitably, not everyone saw eye-to-eye.
The default source for lighting greenhouses is high pressure sodium (HPS). The spectral distribution of the HPS lamp has proven itself over many years to provide the favoured conditions to support plant growth. But the introduction of the LED is set to challenge that.
The scientists were first to present their findings, and suggested from the outset that HPS may be a handy light source but it is far from the best light for plant growth, especially when we look at what plants actually need.
With plants seeking spectral peaks in the blue and red ranges to encourage good growth, the HPS lamp manages to miss out on both of those core needs. It was suggested that the real reason for using HPS is convenience. You get a lot of light for little energy.
One of the underlying benefits of LED technology is its ability to produce light sources tuned to almost any spectral demand. The scientific research is looking at various mixtures of light spectra and intensity, typically using lettuce as the test crop.
That research is demonstrating clear benefits for LED lighting, though scientists, being a cautious bunch, will always decorate their findings with caveats.
Test results showed different outcomes with different salad types, so it is not wise to extrapolate the findings beyond what was tested. We were told that different results are expected with other type of plants and that more research is needed. This is not necessarily a reassuring message for an industry needing certainty before committing to heavy financial investment.
The default source for lighting greenhouses is high pressure sodium, but the LED is changing that.
Throw the LED industry into this mix and watch the frustration bubble over. It is difficult to argue with plant scientists; at least they are growers themselves, even if they are doing it at research centres rather than on the farm. But, to have outsiders telling you that you’ve been doing it wrong all these years was perhaps a step too far for some of our audience. New tech meets established practice. Light blue touch paper and stand well back.
There was nothing different in the information that was presented by the LED ambassadors, and those of us who have got used to being told that the LED changes everything are used to the rhetoric. But this does not necessarily go down well with a conservatively minded horticultural community, and their views were expressed with enthusiasm.
But what does it all mean for the future of horticultural lighting, as we move inexorably towards a world where food security will become an over-riding demand on society and industrial resources?
There can be no doubt that the future for horticultural lighting lies with the LED. The problem to overcome will be the same one that we are experiencing with human-centric lighting; everyone is different and one size does not fit all. This debate will run on and the chances are that even more intelligence will have been gathered on plant systems when the horticultual community gathers in Denver on 17 September 2017 for round two of the debate on Horticultural Lighting.