Automated monitoring - Greenhouse Canada

Automated crop monitoring provides numerous benefits to greenhouse operators, Dr. David Ehret, of the Pacific Agri-Food Research Centre in Agassiz, B.C., told growers attending the annual Saskatchewan Green Trades Conference.

He said it is relatively inexpensive, easy to expand, highly flexible, simple, and reliable. The procedure also provides an early warning system, allows comparison of different zones, seasons and years, and continually gathers information on crop conditions.


Dr. David Ehret of the Pacific Agri-Food Research Centre of Agriculture and Agri-Food Canada.

The lower load cell. (Photo courtesy of T. Helmer)

The upper load cell. (Photo courtesy of T. Helmer)

An overview of the crop monitoring system. (Drawing courtesy of Dr. David Ehret)

Dr. Ehret provided an overview of the research he and his colleagues have conducted. “Our goal was to develop a system that would continuously and automatically record water use and growth in greenhouse vegetable vine crops (tomatoes, cucumbers and peppers).”

The researchers were trying to create a system that is non-invasive and integrates with current greenhouse crop management practices, requires minimal maintenance, monitors groups of plants to reduce variations within the crop and provides information for growers which they wouldn’t be able to obtain in any other way.

The system that Dr. Ehret and his research team developed uses two sets of load cells (scales). The lower set measures water uptake (transpiration), number of irrigation events, emitter feed volume, drain volume and per cent over-drain, along with media weight and per cent media moisture. The upper set measures changes in canopy weight or crop growth, the weight of the harvested fruit, and the weight of the prunings. The degree of water stress that the plants might be experiencing can also be estimated.

The researchers also experimented with light and weight-based irrigation and found that weight-based over-drain is more consistent through the day.

In potted plants, Dr. Ehret noted, load cells measure crop water use, crop growth and changes in substrate moisture.

He also touched on the measurement of starch in leaves to help manage CO2 dosing, as well as the detection of special plant odours which may indicate insect problems. He noted that those systems are still under development and are not ready for public sale yet.

Computer integration is relatively easy for water use and canopy temperature data, but more difficult for growth data. “Predictive models are still being developed,” said Dr. Ehret.

Myron Love is a freelance writer and photographer in Manitoba.

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Relatively inexpensive, such systems offer numerous benefits to growers