Spotlight on plant light requirements

Gardeners can save on lighting in greenhouses and thereby protect both their finances and the environment.

There is money in the bag if the lights are turned off. That goes not only for the average citizen but also for roses, hibiscus and other plants in the greenhouse. Scientists from the Faculty of Agricultural Sciences at the University of Aarhus are participants in a project together with the Maersk Mc-Kinney Møller Institute at the University of Southern Denmark which can save gardeners energy and thereby save money and protect the environment. The aim of the project is to investigate when is the best time to turn off the light n the greenhouse and to develop an IT-tool that turns the light on and off automatically.

Plants in greenhouses receive artificial light for optimal development. How long the light should be on depends partly on the plant type and partly on outdoor light conditions. On a long and sunny summer day there is not as much need for extra light as on a short, cloudy winter day. Nevertheless, the artificial light is on for the same period of time for long periods of the year.

- Greenhouse gardeners use artificial light in large amounts. The light is turned on most of the time just to be on the safe side. By gaining knowledge of when plants best utilize light and constructing a light control program that automatically turns the light on and off, a lot of electricity can be saved, says senior scientist Carl-Otto Ottosen from the Department of Horticulture at the University of Aarhus.

His role in the project is to contribute with input about plant requirements, while researchers from the Maersk Mc-Kinney Møller Institute will develop the software to control the light programme.

- Plants are a bit like people. Some of them react quickly to light while others need more time to wake up and get going. That means that some plants need light for longer periods than others for optimal development. To construct a light control programme we therefore need to know the requirements for each plant variety, explains Carl-Otto Ottosen.

Many gardeners have their own thermal power stations producing electricity. In periods with no requirements for artificial light in the greenhouse the gardener can instead sell power to the electrical grid. The project will also calculate if it is best to sell electricity or to use it for the plants.

For further information please contact senior scientist Carl-Otto Ottosen, Department of Horticulture, Faculty of Agricultural Sciences, University of Aarhus, telephone: +45 8999 3313, e-mail: [email protected]