We may be one step closer to using technology to ensure productive, disease-free crops, thanks to the development of a multifunctional electronic patch ‘worn’ by plants that monitors for the presence of pathogens and environmental stressors.
Smart agriculture, the use of innovative technology to provide information on important factors like water, soil types, and disease, has gained traction as a means of ensuring global food security.
Plant disease results in the loss of around 20% to 40% of crops annually, leading to not only a reduction in food production but also species diversity, not to mention the cost of disease control. According to the Food and Agriculture Organization of the United Nations, it’s estimated that nearly 670 million people – that’s 8% of the world’s population – will be undernourished in 2030.
Plant-worn sensors capable of providing real-time, noninvasive monitoring aren’t a new thing. But existing sensors are limited in what they can monitor, have poor sensitivity, and don’t pick up specific diseases.
Mindful of the importance of maintaining healthy crops, researchers from North Carolina State University developed a more advanced electronic patch that is placed directly on the leaves of plants to monitor for pathogenic infections and environmental stressors.
The patches are small – only 1.2 in (30 mm) long – and made of a flexible material containing sensors and silver-nanowire-based electrodes. They’re placed on the underside of the plant’s leaf, where there are more stomata, the pores that allow a plant to ‘breathe.’ The patches are an upgrade on an earlier version that detected plant disease by measuring volatile organic compounds.
“The new patches incorporate additional sensors, allowing them to monitor temperature, environmental humidity, and the amount of moisture being ‘exhaled’ by the plants via their leaves,” said Yong Zhu, co-corresponding author of the study.
To test their new patch, researchers turned to the humble tomato, one of the most widely consumed agricultural products. Tomato plants are susceptible to many pathogens, including fungi, viruses and bacteria, which substantially reduce crop yields and fruit quality.
The tomato plants, housed in a greenhouse, were infected with three pathogens: tomato spotted wilt virus (TSWV); early blight, a fungal infection; and late blight, caused by a fungus-like pathogen called an oomycete. The plants were also exposed to abiotic (non-living) stressors such as overwatering, drought, lack of light, and high salinity.
“This is important because the earlier growers can identify diseases or fungal infections, the better able they will be to limit the spread of disease and preserve their crop,” said Qingshan Wei, co-corresponding author of the study. “In addition, the more quickly growers can identify abiotic stresses, such as irrigation water contaminated by saltwater intrusion, the better they will be able to address relevant challenges and improve crop yield.”
Experimenting with a combination of sensors, the researchers analyzed their data using a machine learning model to determine what combination was more effective at identifying disease and stress. The model confirmed that, to be most effective, at least three sensors were required.
“Our results for detecting all of these challenges were promising across the board,” Wei said. “For example, we found that using a combination of three sensors on a patch, we were able to detect TSWV four days after the plants were first infected. This is a significant advantage, since tomatoes don’t normally begin to show any physical symptoms of TSWV for 10 to 14 days.”
The researchers say they are close to creating a patch that crop growers can use. They intend to make the patches wireless and then test them in the field, outside of a greenhouse, to ensure they work under real-world conditions.
“We’re currently looking for industry and agricultural partners to help us move forward with developing and testing this technology,” Zhu said. “This could be a significant advance to help growers prevent small problems from becoming big ones, and help us address food security challenges in a meaningful way.”
The study was published in the journal Science Advances.
Wearable plant patch monitors for disease, environmental stressors [New Atlas]