They have unveiled a leaf-mounted sensor with the goal of creating a way to easily tell whether a plant is thriving or dying.
Amid concerns over climate change and overpopulation, they believe this technology could help improve crop yields and resource management to meet ever-growing demands.
In research published in Sensing and Bio-Sensing Research, a team at Tohoku University outline how extreme weather events such as heat waves, heavy rain, and droughts stress plants can reduce crop yields and threaten the long-term health of our farms, forests, and biodiversity.
There is an unmet need, they argue, to monitor precisely how plants respond to these changes. While drones and aircraft have improved plant monitoring from above, they only capture more macro, surface-level information.
They also require adjustments to be able to track plants accurately over time. Other small sensors that can capture changes at the individual plant level are inconvenient since they often require on-site personnel to install and manually check each sensor.
“The traditional methods may work well for some purposes, but they are difficult to operate and quite expensive,” explains Kaori Kohzuma, a researcher at Tohoku University. “In order to continuously monitor small changes, we needed a new solution.”
Attaches directly to underside of leaves
To address these issues, a team of researchers developed a novel sensor that attaches directly to the underside of plant leaves.
This small device uses a spectroscopic sensor and light source to measure leaf colour without blocking sunlight, and it can track changes in the same spot over time. Powered by a battery, with Wi-Fi data transfer and waterproofing, the sensor can work outdoors for over a month, allowing for extended data collection.
In an outdoor trial to test performance under real life conditions, they attached the sensor to birch leaves to track changes in leaf colour during autumn, leaf fall, and aging over two weeks. They were able to observe a decrease in chlorophyll (an indicator of plant stress) and how the plant’s response fluctuated with sunlight intensity.
Real-time fine-tuned readings
“Smart agriculture is a huge time-saver,” adds Kohzuma’s colleague Ko-ichiro Miyamoto. “Farmers don’t have time to manually check every single plant. This sensor is able to provide fine-tuned readings for what’s going on in real time. Then they can react accordingly to areas where plants are experiencing high levels of stress.”
He adds the affordable sensor is a promising tool for accurately monitoring plant health and stress through leaf colour and light reflection data. “Its low cost makes it possible to place multiple sensors across various locations, creating a network for simultaneous monitoring in many spots.”
The researchers believe that this smart diagnosis technology allows for support to be provided in the areas it is needed most. They argue the sensor could be used widely in smart farming, forest health studies, and other areas where detailed plant health tracking is important.
