Source: Tyndall National Institute via Irish Times

Plants aren't very good listeners but they might become good talkers with the help of two research teams at University College Cork.

The €2 million study involves plant scientists and electronics specialists and has developed novel new ways to get plants chatting.

"The whole idea is to use technology to monitor crops," explains UCC's professor of botany Alan Cassells. "We want to communicate directly with the plants."

Your common or garden bean plant might not seem like much of a conversationalist but nothing could be further from the truth, provided you have the right ears for listening. Plant temperature can vary as a function of ambient temperature but also as a result of drought-related stress. Plant colour also gives off subtle clues about nutrient availability.

And "green leaf volatiles" are a particularly rich source of information about a plant's relative condition, Cassells says. These are complex volatile chemicals that rise off the surface of a plant as a result of stresses such as insect or fungal attack.

In some cases the volatiles have evolved as attractants that call in predator insects. Aphid damage releases volatiles that signal "free lunch" to passing ladybirds.

The trick is being able to read the various clues being given off by the plant, Cassells says. "If you can detect these chemical signals then we can activate a response to the infestation. We are talking about sensors that can sense heat, greenness and volatiles."

UCC's National Microelectronics Research Centre, now part of the Tyndall National Institute leads the project with support from Cassells's department of zoology, ecology and plant science.

The Institute is responsible for developing the sensors and hardware needed to respond to the plant signals identified by Cassells's team. Other partners include the Computer Technology Institute of the University of Patras, Greece, where the software to read the signals from the sensors is being developed, and the Eden Project in Cornwall, England. It will demonstrate the concept to the public and later to the trade.

The object isn't to make things easier for the farmer, Cassells explains. It is about reducing unnecessary and expensive farm inputs such as irrigation, fertilizers and pesticides. "Essentially this is about sustainability because it is very difficult to sustain an agricultural system without inputs," he says.

The traditional approach was to drench the entire farm with water if the soil felt dry, blitz all the crops with insecticides at the first sign of bugs and dose everything with nitrates if any of the plants look a bit yellow.

The researchers want to reach a situation where signals from the plants themselves will indicate when and what part of a field might need extra water. Only those sections of a field affected by say aphids will receive insect sprays and fertilizers are only applied when necessary.

Sensor placement is a key issue, he says. There is little point sticking moisture sensors in the ground if tractors can't then drive over them to reach crops. Equally, direct attachment of sensors to the plant isn't the best as they can become dislodged and only note what that one plant is saying.

Rather, the research team is using "proximal remote sensing" to find out what the plants are talking about. Cassells says a typical approach would be to have an array of specialised sensors attached to the boom arms of a tractor-borne sprayer. These would take the plant's analogue signal, convert it to digital and feed it back to the computer software, the "black box" that will interpret the signals and decide what to do. "The black box is how the signals are interpreted to activate an appropriate response," he says. This response would be relayed back to the sprayer booms that would then apply water, pesticide or fertiliser as needed, but only where it was needed and not across the entire field.

We won't have to wait long for an opportunity to hear what plants have to say for themselves. The technology is already well developed and some demonstrations of the technology have already been carried out in Cork, Cassells says. More demonstrations are planned for later this spring at the Eden Project.

Dick Ahlstrom
Source: Irish Times
http://www.ireland.com/newspaper/science/2005/0505/4046882961FTSC5PLANTS.html