Quantifying the effect of soil compaction on three varieties of wheat (Triticum aestivum L.) using X-ray Micro Computed Tomography (CT)

Aims: X-ray Micro Computed Tomography (CT) enables interactions between roots and soil to be visualised without disturbance. This study examined responses of root growth in three Triticum aestivum L. (wheat) cultivars to different levels of soil compaction (1. 1 and 1. 5 g cm ^-3). Methods: Seedlings were scanned 2, 5 and 12 days after germination (DAG) and the images were analysed using novel root tracking software, RootViz3D®, to provide accurate visualisation of root architecture. RootViz3D® proved more successful in segmenting roots from the greyscale images than semi-automated segmentation, especially for finer roots, by combining measurements of pixel greyscale values with a probability approach to identify roots. Results: Root density was greater in soil compacted at 1. 5 g cm ^-3 than at 1. 1 g cm ^-3 (P = 0. 04). This effect may have resulted from improved contact between roots and surrounding soil. Root diameter was greater in soil at a high bulk density (P = 0. 006) but overall root length was reduced (P = 0. 20). Soil porosity increased with time (P < 0. 001) in the uncompacted treatment. Conclusions: RootViz3D® root tracking software in X-ray CT studies provided accurate, non-destructive and automated three dimensional quantification of root systems that has many applications for improving understanding on root-soil interactions.