Sensors: Crops, animal and food safety monitoring

by Tamara Scully
Advances in precision agriculture are allowing farmers to better control inputs and maximize the use of resources. This technology includes Global Positioning Systems (GPS) in the field, robotic milking equipment on dairy farms, mechanical pruning of vineyards, and a variety of tools such as weather monitors or remote soil sensors. Add in the connectivity of things, and the ability to have large amounts of data available not only on the office computer, but on the mobile phone, and high-technology has become second nature to many farmers.
But there are advances still to be made. Monitoring internal plant data in real time is the focus of Abraham Stroock Cornell University Professor of Chemical and Biological Engineering. Stroock spoke on the topic of “Plant Sensors for Crop Management and Phenotyping,” in a recent National Academies of Sciences, Engineering and Medicine webinar. Also featured was Dr. Suresh Neethirajan, University of Guelph, who spoke on “Sensors to Monitor Animal Health and Food Safety.”
Plant physiology
“The true vision of precision agriculture should have real time information about the system that we are managing, and a feedback on an efficient delivery system,” Strook said. “There’s a lot of work to be done.”
The vascular physiology of plants has been ignored by engineers, Stroock said, and tools to monitor plant physiological responses lag far behind those used to understand human physiology.
A better understanding of plant physiology in real time would allow data to be collected and analyzed and assist in both better managing crops — such as when applying irrigation — as well as in the field of plant breeding. The goal would be to understand the internal responses of a plant’s vascular system, and then to select for plants with a particular phenotype which makes them better adapted to a given environmental parameter. Phenotypes can be defined by developmental stress, he said.
Finding plants with specific traits and then associating those traits with genes, and “using that to breed better crops,” thus “filling in that black box between that gene, and the phenotype,” is key, Stroock said. “To gain understanding that will allow us to be more sophisticated both in managing crops, and how we select for them,” is the goal.
Accurately measuring plant tissue development, plant signaling, sugar flux, photosynthetic activity, water availability, or nitrogen levels in soils and plants can lead to advances in management and breeding. Measuring the flux of water and sugar in situ, and in combination with environmental parameters, for example, would help with developing a plant best adapted to water stress.
An example of a phenotype that has helped corn growers to maximize yields per acre is cultivars selected for leaf angle. By finding the gene that controlled leaf angle, breeders could select for plants with narrower angles, allowing for closer planting.
Despite the ability to locate the gene, researchers and breeders are “left blind about the biology that connects the gene to the phenotype Stroock said. “We’ve got to be bringing modern biological measurements out into the field.”
Stroock’s team has focused on water use in agriculture, and is working to develop tools to monitor in situ responses in plants to water stress. They’ve developed a tesiometer containing a microchip, which is plugged directly into the xylem of a plant, providing “a long-term interface with the tissue where that water status is present,” he said.
The tensiometer turns water stress into a voltage, using a micro-scale pressure sensor, a thermometer and a cavity of liquids which is put into equilibrium with the cavity of the plant, creating a “synthetic xylem.” This system is a Micro Electric Mechanical Systems (MEMS), Stroock said, and is easily manufactured and integrated with other technology.
“We’ve adopted the physiology of plants to create this system,” he said. “We can capture even high frequency, rapid changes associated with changes in the local atmosphere,” and allow researchers to see “how plants themselves regulate stress.”
The next steps are to collect more internal physiological data, and to define new traits, such as those that impact water efficiency in a plant. Other types of sensors that can directly obtain information from the internal functions of plants, and apply this to areas such as water use efficiency, are being developed by students in Stroock’s laboratory at this time.
Animal sensors
Meat production is on the rise as global demand increases. Almost double the amount of production today is predicted to be needed to meet 2050 demand. Addressing health concerns from farm to fork can include the development of biosensors and nanotechnology to prevent disease, enhance animal welfare and insure food safety.
New diseases arising from livestock occur about three times each year, Dr. Neethirajan said. Two of these three diseases can be transmitted to humans. Biosensors which can find these pathogens in animals in real time are crucial to animal and human health. On-farm detection and diagnosis of these diseases is the goal.
“The goal is to move the farmers from reactive to proactive through predictive and preventive approaches,” he said.
Re-useable devices which use disposable disease detective microchips to diagnose and quantify pathogenic presence is one goal. These devices would need to use small samples — like a droplet of blood or mucous — to detect specific disease biomarkers. The tests would provide easy to read results, perhaps based on color changes. Strains of disease could also be able to be differentiated, and potential virulence and risk identified.
This sort of testing would be conducted via handheld devices. Data would be transmitted to mobile computers and integrated into existing data systems.
“The diagnosis of the disease involves quantification, and the real-time transmission of the data enhances the bio-surveillance in a much more sophisticated manner,” Dr. Neethirajan said.
Today, samples required to be collected are large, and must be shipped to a laboratory. The cost of this system, along with the delay in results, is not efficient and potentially allows disease to spread unnecessarily.
Beyond on-farm, simple diagnostic tests, the potential for wireless sensors to predict diseases such as Avian Influenza, via non-invasive health monitoring of poultry, is being developed. Systems using wireless sensors and, such as those measuring body temperature and movement, along with Doppler technology to monitor blood flow, could predict disease in an animal or flock before actual onset of symptoms.
Other tools could monitor livestock vocalizations, to differentiate sounds by meaning. Some vocalizations can indicate concerns such as the thirst, heat stress, fear, or hunger. Distinguishing these would provide better welfare monitoring, management responses, and control of disease.
Nanotechnology can also be used in on-farm food safety measures. Testing for allergens or pathogens that cause human food-borne illnesses would monitor food safety before the product leaves the farm.
Other diseases, such as bovine ketosis, could also be monitored and diagnosed via on-farm bioelectronic techniques. Wearable biosensors would monitor animal health. The presence of biochemical markers in blood or milk would indicate illness.
“Biosensor based diagnosis provides a number of benefits in terms of enhancing food safety,” Dr. Neethirajan concluded.
The webinar can be viewed at http://nas-sites.org.

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