Plants, like human nerve cells, communicate by electrical impulses. Electrical pulses travel through plant tissues, causing unexpected movements or warning of recently caused wounds.

Now, researchers have used similar logic to enhance plant development, discovering that zapping barley seedlings with electricity causes new shoots to grow faster.

What appears to be fun might be a major boost to food supply at a time when food security has become more essential due to wars and climate change.

According to the United Nations Food and Agriculture Organisation, between 691 and 783 million people suffered hunger in 2022, a 122 million rise from 2019.

Researchers have previously experimented with electricity to increase agricultural yields, subjecting barley, pea seedlings, and Arabidopsis thaliana, a mustard-family plant, to strong electric fields.

A low-power hydroponic system

To lower the energy needs of such devices, the Swedish researchers behind this new study devised a low-power hydroponic system that delivered a tiny but steady voltage to barley seedlings (Hordeum vulgare cv. 'KWS Irina') for five days.

Hydroponic systems replace soil with water, grow year-round, and use less fertiliser than traditional agricultural methods since nutrients and water can be recycled throughout the system.

Hydroponics is frequently used to cultivate lush green crops in dry environments such as Antarctica, and one of its appeals is the ability to stack systems to create space-saving vertical gardens. While hydroponic farming clearly has many benefits, it is the only possible solution to improve food security, and it happens to be particularly suited to "areas with little arable land and harsh environmental conditions," according to bioelectronics researcher and study author Eleni Stavrinidou of Linköping University.

Electrically stimulated plants had 50% more tissue

So Stavrinidou and colleagues placed 5-day-old barley seedlings on specially designed scaffolds and applied a modest electrical voltage for five days. They were then left to develop for another five days before harvesting.

The scientists recycled a conductive polymer and cellulose, a key component in plant cell walls, to create the scaffold, which they termed 'eSoil'.

After 15 days of development, electrically stimulated plants had 50% more tissue by dry weight and were 30% longer than untouched plants.

It's unclear how the continuous hum of electricity boosts plant development. One hypothesis is that electrically stimulated plants are more effective in absorbing nutrients.

However, after 15 days, there were no variations in nitrogen levels between the seedlings with and without electrical stimulation.

In later trials, the researchers discovered that stimulated plants metabolise nitrate more efficiently, resulting in lower levels of the inorganic nitrogen molecule than their non-electrified counterparts, implying that it was transformed into nitrogen-containing biomass.

"But it's not clear yet how the electrical stimulation impacts this process," Stavrinidou explains.

Surprisingly, the researchers noticed that the seedlings' growth spike occurred five days after the electrodes were turned off, rather than immediately following electrical stimulation.

This shows that even little levels of electrical stimulation might have long-term effects on plants.

"However, our work focused on seedlings, and therefore, more studies are required to show whether growth enhancement by stimulation treatment at the early stages of growth impacts the whole growth cycle of plants," the researchers write in the report.

In order to produce enough food for everyone on the planet in a sustainable manner, there are several other aspects to take into account in addition to plant growth and crop yields.

The study was published in PNAS.

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