This discreet sensor, which attaches to the underside of leaves, enhances efficiency by allowing for real-time, remote observation of plant health.
As concerns about climate change and population growth mount, there’s an urgent need to increase agricultural productivity. Researchers at Tohoku University have developed a leaf-mounted sensor designed to easily determine if a plant is healthy or in distress. This compact yet powerful device could play a significant role in boosting crop yields and optimizing resource use to address rising demands.
Severe weather events, such as heatwaves, heavy downpours, and droughts, put stress on plants, reducing crop yields and threatening the sustainability of farms, forests, and overall biodiversity. There is a growing necessity to closely monitor how plants respond to these challenges. While drones and airplanes provide some aerial monitoring, they often only deliver broader, surface-level data and require adjustments for ongoing accurate tracking. Additionally, portable sensors capable of observing changes at the individual plant level often rely on on-site personnel for installation and regular checks, making them cumbersome.
“Traditional methods can be effective for certain tasks, but they can be difficult to manage and relatively costly,” says Kaori Kohzuma. “To constantly monitor minor changes, a new approach was essential.”
In response to these challenges, a research team developed an innovative sensor that directly mounts to the underside of plant leaves. This small instrument employs a spectroscopic sensor and a light source to assess leaf color without obstructing sunlight, allowing it to monitor changes in the same location over time. It operates on battery power, features Wi-Fi data transmission, and is waterproof, enabling it to function outdoors for over a month for prolonged data collection.
“Smart agriculture saves a lot of time,” states Ko-ichiro Miyamoto. “Farmers can’t afford to manually inspect every single plant. This sensor delivers precise, real-time readings of plant conditions, enabling timely responses to areas where plants are under severe stress.”
The sensor performed admirably when tested against a commercial spectrometer on nearly 90 leaves from 30 different species. It successfully differentiated colors across seven of the eight wavelengths it can detect, and its readings at 620 nm closely matched those from commercial chlorophyll meters. Further evaluations with a stress-sensitive Arabidopsis thaliana mutant confirmed that shifts at 550 nm aligned with the plant’s stress responses and correlated with the well-established Photochemical Reflectance Index (PRI).
During outdoor trials to evaluate practical use, the researchers attached the sensor to birch leaves to monitor changes in leaf color through the fall season, witnessing transformations over two weeks. They recorded a decline in chlorophyll levels, an indication of plant stress, and observed how the plant’s response varied with sunlight intensity.
“This cost-effective sensor is a promising solution for accurately assessing plant health and stress using data related to leaf color and light reflection. Its affordability allows for the deployment of multiple sensors across various locations, facilitating simultaneous monitoring in numerous areas,” Kohzuma explains.
This smart diagnostic tool provides targeted support where it’s most needed. Its applications could extend vastly into smart farming, forest management studies, and other fields where precise tracking of plant health is crucial.
The findings of this research were published in Sensing and Bio-Sensing Research on September 24, 2024.
