The X-factor: visualizing undisturbed root architecture in soils using X-ray computed tomography

Abstract

Although roots play a crucial role in plant growth and development through their acquisition and delivery of water and nutrients to the above-ground organs, our understanding of how they interact with their immediate soil environment largely remains a mystery as the opaque nature of soil has prevented undisturbed in situ root visualization (Perret et al., 2007). However, new developments in non-invasive techniques such as X-ray computed tomography (CT) provide, for the first time, an exciting opportunity to examine detailed root architecture in three dimensions (3-D) in undisturbed soil cores (Fig. 1). Although other non-invasive 3-D visualization procedures exist, X-ray CT is viewed as the most appropriate technique for studies of soil:root interactions as the presence of iron and manganese ions may provide interference when alternative techniques such as Nuclear Magnetic Resonance (NMR) are used (Heeraman et al., 1997). Detailed understanding of interactions between roots and their immediate soil environment is vital when considering issues such as land degradation as soil structure is a primary factor determining the availability of edaphic resources such as water and nutrients (Lynch, 1995), and is extrinsically linked to plant productivity (Moran et al., 2000). In view of the rapidly increasing human global population and the threat posed by climate change, maximizing crop yields and developing sustainable soil management strategies are vital for food security.