8 | New Scientist | 22 January 2022A TEAM of researchers claims to
have shown that a high-voltage
electric field generated using wind
and rain can boost crop yield, but
other scientists say the results
should be treated with caution.
The effectiveness of using
electric fields to stimulate crop
growth, known as electroculture,
is far from established, despite
being tested in Europe, the US
and China. A “golden age” is
dawning for the technology,
one Chinese scientist told
New Scientist in 2019.
Now, Jianjun Luo at the Chinese
Academy of Sciences in Beijing
and his colleagues have grown
two sets of peas in a greenhouse,
one of which was exposed to an
electric field. Previous tests have
drawn electricity from the grid
to create the field, but Luo’s
one used a small device – a
triboelectric nanogenerator – to
generate it from wind and rainfall.
The result: pea yields increased
by almost a fifth, and the plants
germinated faster than the
control peas too (Nature Food,
doi.org/hcrz). “The main advance
is that the self-powered systemcan boost crop yield by harvesting
the wasted wind and raindrop
energy in our daily life,” says Luo.
He says the generator system
that the group used cost less
than $40. The team writes that the
approach could be “immediately
and widely applied” to increase
food production and curb
agricultural pollution.
Ellard Hunting at the University
of Bristol, UK, says what is really
new here isn’t growing crops withan electric field but using rain
and wind power to provide the
electricity to do it. “You could also
achieve this with wind turbines
and solar panels, but their
approach is cheaper,” he says.
Jean Yong at the Swedish
University of Agricultural Sciences
says while the engineering is
novel, the way the experiment
was conducted limits the
biological data available on
the plants. “It cannot lead
them towards providing an
explanation for increasing yield
or cutting pesticides,” he says.Luo suggests that the
mechanism for how electric fields
might increase yield could be
photosynthesis, based on his
analysis showing the peas
under the electric field had
more chlorophyll. But exactly
how electric fields affect crops
remains unclear. “That’s the big
question, and nobody really
knows,” says Hunting.
There may be other
explanations for why the peas
exposed to an electric field grew
faster. The trial wasn’t “double-
blinded”, so the technicians
growing the plants knew which
were in an electroculture.
Sarah Driessen at RWTH Aachen
University in Germany says one of
her main concerns with the study
is how overly confident it is that
electroculture works. “The authors
represent it as a fact that static
electric fields promote seed
germination and plant growth,
although this is highly debatable,”
she says. “The authors do not
elucidate the current state of
knowledge on this topic properly
and the basis for their hypothesis
is rather poorly supported.” ❚Adam VaughanSH
UTTE
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DAgricultureCan electric fields help plants grow?
Claims that a wind-powered device can boost crop yield don’t convince other scientists
Pea plants growing
in a greenhouseNews
BiotechnologyA swimming robot
powered by
photosynthesisA ROBOT piloted by a ball of algae
can swim through water and
move around obstacles, powered
only by photosynthesis.
Neil Phillips at the University
of the West of England, UK, and
his colleagues wanted to build
a robot with no electronic parts,
meaning it wouldn’t interfere with
any electromagnetically sensitive
measurement instruments. The
team inserted a marimo, a ball ofalgae that forms naturally in
freshwater currents, inside a
3D-printed plastic spherical shell
equipped with vents. When the
group submerged the shell in
water and exposed it to light, the
marimo produced oxygen from
photosynthesis, which pushed
the shell away from the light.
“We’ve looked at a different
way of doing things,” says Phillips.
“We’re going back to biological
processes, so, in this case, there are
no motors, there are no electronics
or storage systems, you’re basically
just using photosynthesis.”
The robot can carry basicmeasurement instruments and
navigate obstacles by floating
around them. It can’t be steered
manually, making it unsuitable
for some tasks, but it could beused for simple investigations
such as testing water quality.
Because the system is so simple,
it is reliable, easy to repair and can
be made for about £25 per robot.
While other robots have used
elements of photosynthesis for
motion, this is the first to be
powered fully by an organism, no
wires required (Journal of Biological
Engineering, doi.org/hcrj).
“The system works and they
can make it so simply because
they’ve trapped an organism
in there,“ says Jonathan Rossiter
at the University of Bristol, UK. ❚
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A marimo is a ball
of algae that forms in
freshwater currents