"We're super excited about the results of this lighting study, as growers can have a 'Green Conversation' for the first time. Roughly speaking, we 'ask' the plant how it feels about producing more biomass, and based on the 'reply' we get, adjustments are immediately made to the growing conditions," says Dr. Jim Stevens, Senior Innovation Consultant at InnoPhyte, a provider of Science-as-a-Service startup.
This UKRI-funded research focuses on a vertical farming system for cultivating basil that optimizes light usage by adjusting it in real-time to meet the plants' needs, addressing the challenge of high energy costs. Amongst others, InnoPhyte aims to show how chlorophyll fluorescence could be used in a feedback system. At the heart of the device is a chlorophyll fluorescence probe linked via computer to LED lights, allowing it to detect plant stress and adjust light intensity accordingly.
Drop in energy cost and peak in yield
"We were able to boost basil yield by 7%, likely due to the plant's source-sink balance," Jim highlights. When the lights are on, the plant produces sugars through photosynthesis, the source, which then needs to be distributed to various parts of the plant, like stems, roots, or fruits, the sink. "By adjusting light intensity, we believe the plant can manage this balance more effectively, putting more energy into growth and yield, and less into repairing damage."
The result was that we could improve yield and drive down energy use simultaneously. "Contrast this to techniques currently deployed in CEA, where the environment is controlled with fingers crossed that it's what the plant needs." As James explains, chlorophyll fluorescence was first observed in the 1930s: if you shine a very bright blue or red light on a plant, its chlorophyll will fluoresce red. Fluorescence is proportional to plant stress. We can also increase or decrease that stress by altering light intensity.
Tests showed the system could increase crop yields, lower energy use, and significantly reduce the environmental impact of growing food indoors. By improving how resources are managed, this approach aims to make indoor farming more productive, cost-effective, and sustainable, helping to address global challenges like climate change and food security.
Researchers noticed that plants consistently need less light later in the photoperiod. Jim adds, "By reducing excess light in the latter part of the day based on plant feedback, we were able to cut energy costs by 6% while also increasing productivity."
Opportunities beyond basil
"There's potential to apply this approach to other crops," says Jim. For this trial, basil was used as it's a high-value leafy green with strong demand in the UK, Jim points out, but many other plants could benefit from long growing periods under optimized light conditions. "A grower could also adjust system settings to prioritize either reduced energy use or increased biomass, depending on their goals. For example, the approach might differ for a commodity crop compared to a specialist pharmaceutical crop."
Jim believes that this work opens a whole new field of research in plant productivity, as light intensity was the only element studied. Light quality, e.g. which parts of the spectrum you use, is also important. Further work might focus on quality metrics such as texture, nutrition, or secondary metabolites, which are also of interest.
"Meanwhile, requirements might vary not only by crop but also by developmental stage, as we already know that vegetative and reproductive growth have different lighting demands," he claims. The work could also be extended to other environmental parameters, temperature, RH, and nutrition are obvious examples. "Finally, this approach offers an alternative to breeding to match plants to environments."
"This is a world first in directly connecting the plant and its environment. For us, it is a first step in exploiting non-invasive techniques to control and direct productivity in real-time. Other sensing techniques, better feedback systems, a deeper understanding of environments and novel varieties will all contribute to a step change in the operation of CEA. This is a great example of how UKRI-funded research can deliver real-world benefits from the lab bench," says Tracy Lawson, Professor at the University of Essex. "We're proud of the 'Green Conversation' work we did with colleagues at the University of Essex including Dr. Jim Stevens, Dr. Philip Davey, Dr. Tanja Hoffman, and Mr. Piotr Kasznicki."
For more information:
Innophyte Consulting
Jim Stevens, Senior Innovation Consultant
[email protected]
https://innophyte.co.uk
University of Essex
Tracy Lawson, Professor at School of Life Sciences
[email protected]
essex.ac.uk