Researchers use sensors to track crops

The University of Arizona’s agricultural department uses sensors to enhance high throughput genotyping of crop varieties


MARICOPA, Ariz. — Sensors installed on a homemade mobile platform at the University of Arizona’s Maricopa campus helps researchers quickly understand the response of a diversity panel to a specific set of conditions.

A diversity panel is a collection of genetic material, in this case germplasm of an agricultural crop.

“It is a moving platform driven with hydraulic power, diesel engine on the rear side. In the front we have added a number of sensors we use in co-ordination with the water treatments we use when we test these crops,” said Pedro Andrade, an agricultural biosystems engineer at the University of Arizona.

Maricopa is in the state’s low desert with high temperatures and low relative humidity and is a good place to test for heat and drought tolerance of different cultivars.

Researchers run projects every year at the campus that deal with the abilities of plants to cope with heat.

The sensor platform is only one example of how the university is using sensors to enhance its high throughput genotyping of crop varieties.

He said everything in the research and extension program at the Maricopa Agriculture Center is geared toward field conditions, and the indoor testing phase of sensors is only for integrating different sensor systems.

Andrade said it’s an exciting time to be an agricultural engineer.

“Putting machines together, integrating different systems, different components to characterize the growth and the health of these crops under field conditions,” Andrade said.

“The front mounted frame is sensing the spectral response of the crop in two wavelengths. That gives us NDVI information that’s a measure of the vegetation. It’s a good index to give us a good idea of the size of the plants and the greenness of the plants.”

There’s also a thermal radiometer that gives information on the canopy temperature, which provides researches an indication if plants are expressing heat stress by increasing the temperature of the canopy.

“We also have a one dimension displacement sensor. These are ultrasonic sensors. They are very good units to measure the heights of the plants. Many times between the height and the NDVI spectral response we can have a very good characterization of how those plants are performing under these environmental conditions,” Andrade said.

Researchers have also incorporated scanning lasers, a LIDAR type of sensor that provides information on plant width and gives a two dimensional representation of the size of the plants.

“They are also really good for giving information on plant height, but it’s more than plant height. It’s also giving us a profile of the plants that are adjacent to each other within a research plot,” Andrade said.

“Right there you have two dimensions, but when you integrate the data in the direction of travel, then we can have 3D parameters generated. But that’s post processing.”

The instantaneous output that the scanning lasers provide involves plant height and plant canopy cover.

The data collected by the sensors is referenced with an ultra precise RTK GPS or GNSS receivers with the help of data loggers housed in boxes on the platform.

Researchers have also installed cameras that were developed for drones.

“The camera is built to be deployed from a certain altitude. We’re bringing it much closer to the ground. That way we generate imagery that can be related to how the plants are responding. We’re analyzing four different wavelengths,” Andrade said.

He said the primary work of the sensors at the research station is for high-throughput genotyping characterizing or analyzing specific characteristics on a diversity panel under controlled conditions.

However, researchers also use the sensors on crop varieties already adopted by growers.

“In that case, what we are after is to generate recommendations for management, which I will say is a part of our work that is closer connected to the producer than with the providers of technology,” Andrade said.

For example, researchers at the station use the mobile sensor with cotton to understand the ideal status of the crop.

“If the crops are lagging behind, then added fertility can be a management decision that can be done the same day. We estimate the number of nodes with weather information and we estimate plant height on a continuous basis with thee kind of sensors,” Andrade said.

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