Plants cannot complain when the heat gets unbearable or water becomes scarce. But they do send out distress signals, and scientists have developed a tiny sensor that could help farmers detect them before crops show visible signs of damage.
The coin-sized device, developed by engineers at Saudi Arabia’s King Abdullah University of Science and Technology (KAUST), can monitor stress inside plant leaves in real time without seriously harming them.
The technology could eventually help farmers respond earlier to extreme heat, drought and other environmental stresses, including the prolonged dry conditions associated with El Niño that threaten agricultural production.
The science behind the device centers on hydrogen peroxide, a chemical that plants naturally produce in small amounts to help regulate their defenses against diseases and other threats.
When plants experience excessive heat or intense light, however, their cells can produce a surge of the chemical. Too much hydrogen peroxide can damage plant tissues, making it a useful warning sign that a plant is under stress.
The problem has been measuring these changes without cutting into plants or collecting samples that could damage them.
The researchers addressed this with a graphene-based sensor, made using a laser, fitted with microscopic needles that penetrate leaves and draw tiny amounts of fluid for analysis.
At just 0.4 millimeters wide, the needles are small enough to monitor what is happening inside a plant without causing serious injury.
In experiments involving aloe vera plants, the sensors detected rising hydrogen peroxide levels almost immediately after the researchers exposed the plants to unusually bright light.
The response was stronger when the plants were kept at 28 degrees Celsius than at the normal growing temperature of 19 degrees Celsius. In both cases, the chemical levels began falling after about an hour.
The findings, published November 12 in the journal Cell Reports Physical Science, demonstrate how quickly plants react to changes in their environment, even before their leaves show obvious signs of distress.
The potential payoff could be significant for farmers, food agencies, as well as consumers.
During El Niño, for example, crops exposed to prolonged heat and inadequate water may suffer before visible wilting or other damage alerts farmers that something is wrong. An early-warning sensor could eventually help identify stressed plants sooner, allowing farmers to prioritize irrigation, adjust water use and intervene before losses become severe.
That could be particularly useful in water-scarce farming areas, where every drop counts and applying irrigation at the right time can make a difference to yields.
The researchers caution, however, that the technology is not yet ready for widespread agricultural use. It still needs to be tested on different crops, including commercially important food plants.
The larger promise is to give farmers a way to see what their crops are experiencing, rather than waiting for leaves to turn yellow, wilt or otherwise signal that trouble has already arrived.
In farming, as in human health, catching a problem early is often better than treating the damage afterward. And unlike farmers, plants do not have to wait until harvest to reveal that something went wrong.
