Researchers at the Australian Plant Phenomics Facility at the University of Adelaide are investigating improving yields of grapevines using hyperspectral imaging. The hyperspectral cameras and software were developed by the Fraunhofer Institute for Factory Operation and Automation IFF in Magdeburg.
Images of grapevines were captured from the air to generate a spectral map of the plants and examine their chemical constituents and nutrient levels. This information enables viticulturists to cultivate grapevine varieties that are best suited to growing in the local conditions in Australia, where soils can be dry and salty and summer temperatures are often extremely high.
Hyperspectral imaging gathers spectral information over a range of wavelengths (see the article ‘Building a spectral picture’ in the April/May 2013 issue), and can be used to determine the chemical composition of plants. This then tells farmers how healthy their crops are.
Speaking about Fraunhofer’s hyperspectral imager, project manager at Fraunhofer IFF, Professor Udo Seiffert, commented: ‘The camera chip we use covers a large area of the relevant wavelength spectrum and, together with appropriate software, is able to scan the biochemical composition of every single recorded pixel precisely.
‘Our data processing is based on mathematical modelling. On the basis of these algorithms, the software recognises characteristic absorption properties of defined target constituents and filters them out of the raw data,’ said Seiffert.
Initially, the researchers had to calibrate the software by photographing reference plants in order to obtain a spectral fingerprint. Laboratory analysis then determines the concentrations of the relevant chemical constituents, which are entered into the mathematical model together with the hyperspectral fingerprint. Once the software has learned the correlation, it automatically filters the relevant constituents out of the hyperspectral camera images meaning further laboratory analysis is not required.
One benefit of hyperspectral imaging is that farmers can concentrate on cultivating plants that thrive particularly well under the prevalent climatic conditions, thus enabling them to irrigate their fields less, for instance.
Diseases such as fungal infections can also be detected faster thanks to hyperspectral technology. An infested plant activates defence mechanisms before an infection becomes outwardly visible, by dead leaves, stalks or mildew. Theses mechanisms indicate that the plant has detected and is combating the infection. Previously, such tests required lengthy experiments in greenhouses. Aerial photos can be used to detect sources of infection in a field quickly.
The Fraunhofer camera will be on display at Biotechnica in Hannover, 8-10 October.
