Utilizing CT Technology to Answer Unsolved Questions in Ornamental Tree Root Research

Direct observations of finest root morphology are inherently difficult because of the opaque and heterogeneous nature of soil matrices. Moreover, direct measurements of root morphology traditionally involve destructive harvesting of root material, or root visualization along a two-dimensional surface. Advances in recent x-ray computed tomography (CT) scanning technologies have yielded improvements in image resolution, but there are still many opportunities to authenticate, improve, and apply CT for use in root research and potted plants in particular.  My lab’s research demonstrates the use of CT for answering multiple questions at different scales. I will discuss two projects utilizing CT technology to answer relevant belowground inquiries including micro-CT for quantifying fine root growth as a function of neighbor identification and the adoption of large scale CT scanning systems capable of accommodating larger ornamental trees for root system distribution and growth analysis in a nursery mix substrate in pots. Multiple medical imaging software packages were utilized to stack the sequential CT scans, effectively increasing the visible rooting volume and depth to improve image analysis of root growth and belowground competition.  Individual root identification was performed manually and semi-automated during image analysis as a means of increasing image processing speed while maintaining accuracy. These two studies represent the first in situ, non-destructive comparison of a) root neighbor interactions between two tree seedlings and b) tree root growth over time on whole root systems of 10 maturing tree species.