Optimisation of X-ray micro-tomography for the in situ study of the development of plant roots

X-ray micro-tomography is a well-established technique for non-invasive, three-dimensional imaging of heterogeneous materials. A new application for high resolution low-dose tomography is the study of the development of plant roots. A cone-beam tomography system has been designed specifically to image the early development of plant seeds after germination, with a cubic voxel linear dimension of 100 μm, over a sample diameter of 25 mm. The X-ray source is a 50 kVp silver target X-ray tube which is quasi-monochromaticaly filtered about the 22 keV characteristic K_a silver peak. A 10 cm diameter X-ray image intensifier (XRII) is used to collect the two-dimensional projection images. The rotating sample table incorporates a linear translation mechanism to eliminate ring artefact that is commonly associated with 3^rd generation tomography systems. Developing wheat seeds (Triticum aestivum) have been imaged using the system and the root lengths and volumes measured. The X-ray dose to the plants was also assessed and found to have no effect on the development of plant root