Electronic ‘soil’ improves crop growth

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Eleni Stavrinidou, associate professor and leader of the study, and Alexandra Sanden, PhD, one of the lead authors, connect eSoil to a low-power source to stimulate plant growth.

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Credit: Thor Balhead

Barley seedlings grew an average of 50% more when their root system was electrically stimulated through a new cultivation substrate. In a study published in PNASresearchers at Linköping University have developed an electrically conductive ‘soil’ for soilless growing known as hydroponics.

“The world’s population is increasing, and we also have climate change. So it is clear that we will not be able to meet the nutritional needs of the planet with the existing agricultural methods alone. But with hydroponics, we can also grow food in an urban environment in very controlled conditions,” says Eleni Stavrinidou, associate professor at Linköping University’s Organic Electronics Laboratory and head of the Electronic Plants group.

Her research group has already developed an electrically conductive growing substrate suitable for hydroponic cultivation, which they call eSoil. Researchers at Linköping University have shown that barley seedlings grown in conductive ‘soil’ grew up to 50% more in 15 days when their roots were electrically stimulated.

Hydroponic farming means that plants grow without soil, needing only water, nutrients, and something their roots can attach to – a substrate. It is a closed system that allows recirculation of water so that each seedling gets exactly the nutrients it needs. Therefore, very little water is required and all the nutrients remain in the system, which is not possible with traditional cultivation.

Hydroponics also allows for vertical cultivation in large towers to maximize space efficiency. Crops already grown this way include lettuce, herbs and some vegetables. Grains are not usually grown hydroponically except for use as fodder. In this study, researchers show that barley seedlings can be cultivated using hydroponics and that they have a better growth rate thanks to electrical stimulation.

“This way we can make the seedlings grow faster with fewer resources. We still don’t know how it actually works, which biological mechanisms are involved. What we found is that seedlings process nitrogen more efficiently, but it is still unclear how electrical stimulation affects this process,” says Eleni Starvrinidou.

Mineral wool is often used as cultivation substrate in hydroponics. Not only is this non-biodegradable, but it is also produced in a very energy-intensive process. The electronic cultivation substrate eSoil is made from cellulose, the most common biopolymer, mixed with a conductive polymer called PEDOT. This combination as such is not new, but this is the first time it has been used to cultivate plants and to create an interface for plants in this way.

Previous research has used high voltage to stimulate roots. The advantage of the “soil” of the Linköping researchers is that it has very low power consumption and no danger of high voltage. Eleni Stavrinidou believes that the new study will open the way for new research areas to further develop hydroponic cultivation.

“We cannot say that hydroponics will solve the problem of food security. But it can definitely help especially in areas with little arable land and harsh environmental conditions.”


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