Efficient discrimination of oat and pea roots by cluster analysis of Fourier transform infrared (FTIR) spectra

Understanding belowground competition of plants requires a simple method for species identification of plant roots. This study investigates Fourier transform infrared (FTIR)-attenuated total reflexion (ATR) spectroscopy followed by cluster analysis for the discrimination of pea and oat roots. Pea and oat plants were grown under various conditions – in moist paper, soil-compost mixture, soil, in the greenhouse and field – to enhance the intra-species variability of their chemical composition. FTIR-ATR spectra of young-to-old roots from four independent experiments were recorded and represent, like a fingerprint, the chemical sample composition such as lipids, proteins, carbohydrates, etc. To group the spectra according to their spectral similarity in a dendrogram, cluster analysis was performed. The experimental approach discriminated pea and oat roots 100% successfully. The perfect discrimination of pea and oat roots, even from intercropped plants, strikingly demonstrates the potential of the method.