‘Activated air’ seed cleaning ‘accelerates germination’

By Fred Searle

A new chemical-free seed-cleaning technology developed by Loughborough University spinout Zayndu has been shown to accelerate the growing cycle of baby leaf salads in vertical production.

Trials of the start-up’s ‘activated air’ seed-cleaning system showed that baby leaf salad crops germinate a day faster following treatment.

London-based vertical farming tech firm Vertical Future carried out the trials and senior plant scientist Dr Katie Wilkins said: “We’ve seen some amazing results, particularly for crops such as Amaranth, where treated seeds have resulted in significant reductions in infections, improved germination rates, higher yield and reduced losses.”

The company is collaborating with Zayndu and NIAB on CHOPS (CEA Heirloom Optimisation and Pathogen Control of Seed), an Innovate UK-funded project to create a quality-marked, high health status seed system.

Vertical farms are closed systems, so are vulnerable to rapidly spreading fungal diseases. To prevent this, the highest levels of hygiene are required, including cleaning seeds to remove fungal spores, the options for which are currently limited.

Zayndu’s activated air technology is completely dry and chemical-free. The company launched its small mobile unit Aurora Z10 earlier in 2021 to allow small batches of seeds to be disinfected by growers as required.

For the first time, it enables certain high-value seeds such as tomato or fast-growing seeds like rocket to be disinfected, and it could allow more species to be grown in a controlled environment in future.

CEO of Zayndu, Ralph Weir, explained that the technology uses a ‘cold plasma’ generated when an electrical current moves through air, splitting the oxygen and nitrogen molecules and creating a powerful disinfectant with no residues.

“Our initial focus was removing fungal spores from seeds, and this has been successful,” he said. “We then observed that treated seed was germinating faster and had a higher germination success rate. For crops such as microgreens, where there is a 10-day cycle, on or two days faster germination will have a massive impact on productivity.

“Cleaning seed with activated air has the potential to increase productivity by 10 per cent or more and reduce the risk of fungal disease, without the need for chemicals or hot water.”

Dr Jane Thomas, senior pathologist at NIAB, added that Zayndu’s cold plasma treatment was “a good technology and one of the few options available for vertical farming”.

“The alternatives are hot water treatment, which can knock back germination of viable seed, or possibly UV lighting, which has the potential to damage the seed,” she said.

“The accelerated germination rates are very interesting. It could be that the treatment is ‘priming’ the seed by physically altering its coating which is encouraging rapid germination.

“Salad leaves are a short-lived crop, so reducing the cycle by a day will have a big benefit for productivity, allowing more harvests within a fixed period and space.”

Weir added that Zayndu’s new technology “can be a godsend” for vertical farmers, particularly those growing crops such as pea shoots which carry high fungal loads.

“Infected pea shoots become slimy, smell horrible, and lead to the crop being destroyed – and they may infect other crops within a tightly-packed vertical farm,” he said. “Removing the fungi would make it easier to grow high-value pea shoots in a controlled environment.”

Zayndu is offering a new batch-testing service, and breeders and growers who want to see the results for themselves can contact them at seedhealth@zayndu.com.

The company is set to announce the findings of its trials at the online Global Vertical Farming Expo (GVFE) 2021 on 1-2 December.