Minirhizotron Systems

minirhizotron imaging system, root imager, MR camera, MR scanner

Root and mycorrhiza development are key for plant performance and affect many ecosystem and biogeochemical processes. However, observing this hidden half of ecosystems is not easy, being covered in the soil. Minirhizotron systems are a qualitative and quantitative observation tool to study root and hyphal growth, longevity and distribution in situ or mesocosms experiments. The MR system is based on transparent glass or plastic tubes (MR-T) inserted tightly into manually or mechanically established holes. Subsequently an imaging device is inserted into the tube in order to record images of roots and rhizosphere seen through the MR tube walls. The images are then recorded and processed by a control unit (handheld or laptop).  Capture Full-HD images of living roots and mycorrhizal hyphae in soil to monitor growth and behavior over multiple seasons with the VSI Minirhizotron systems!

Getting to the root of the matter!

Pisum sativum root
Pisum sativum root in a sand/humus-filled pot. Image was captured with the standard VSI minirhizotron camera.

The VSI minirhizotron camera systems are composed of modular units and specific features can be combined to highly customized devices -fitting both scientific needs and funding situation. Our minirhizotron cameras are available either as fixed- or variable-diameter systems for MR tubes of 5-10 cm inner diameter – allowing for continued use of available tubes and to easily upgrade older imaging systems. The imaging process can be completely automatized including tube recognition and imaging of pre-set or previously imaged locations, but systems with manual indexing ("Smucker handle") are also available. In any case, precision in terms of imaging quality and repeatability of imaging locations and ease-of-use is key. All imaging systems allow to capture Full HD images of selected areas (360°), easily allowing to adapt the size of the monitored MR-T surface to research needs and resources for image analyses. The minor image distortion of original images, caused by the curved tube surface, can be (automatically) corrected by the included software. Image size (standard: 20 x 20 mm) can be adjusted, allowing to align root length observations from MR-Ts e.g. to biomass sampling depth (e.g. 0-10 cm, 10-20 cm, ...) without resizing images. Imaging a depth gradient at a time, on predefined sides of the MR-T, is recommended when using angled MR-Ts -allowing for more accurate soil depth determination then in other systems own the market. The minirhizotron imaging systems are either programmed and operated by a handheld or a laptop; both wireless (approx. 10 m radius for remote-control-release) and cable-bound options are available. Devices are powered by Li-ion batteries (>10 h operation time @ 10-30°C) or power line (110-230V). Image naming follows the ICAP-scheme (ExpName_T001_L001_Date_Time_001_Op.jpg) to be compatible with analyses software world-wide (see below). In addition, a section number can be given instead of the operator name to distinguish multiple "imaging transects" (depth in vertical MR-Ts, angle in horizontal MR-Ts) within the same MR tube.

Minirhizotron Imaging systems, Design options

Technical Specifications of MR Cameras (Overview)

  • One or by-directional, Full HD color images with live preview, 360°-imaging; picture size dependent on tube diameter and software adjustable (for Bartz system-sized tubes, for example, the standard size is 20 x 20 mm)
  • Autofocus, manual focus option to correct for tube bends, crevices and different tube-wall diameter 
  • LED lighting, software controllable, scattering filters to minimise reflections on tube walls 
  • Versions for fixed- or variable minirhizotron tube (MR-T) diameter (di = 5-10 cm); inclination: vertical or angled, horizontal or even upslope (advanced version)
  • Suitable MR tube lengths: 100 to 700 cm (omni wheel-type), 20-150 cm (gear rack-type), 20-400 cm (indexing handle-type); tube wall thickness 1.5-6 mm (manual focus can be adjusted accordingly)
  • Manual ("Smucker" indexing handle-type) and/or fully automatic positioning and imaging; precision positioning systems; zero positioning manual (with adaptor) or automatically according to sensor readings; sensor preventing accidental instrument immersion in water-filled tubes
  • Rechargeable battery (>10 h @ 10-30°C) and/or power-line (110V/220V) operated (Standard)
  • Operated with custom-made software interface on handheld (wireless) or laptop (cable), image capturing by remote-control-release optional (Bluetooth)
  • Software: predefine experimental set-up and tube properties (e.g. tube length aboveground); set imaging pattern for each tube separately or homogeneously; live image preview (optional, reduces maximal imaging speed slightly); set automatic imaging intervals (device needs to remain in tube) e.g. for time-lapse movies; Image distortion caused by round tube surface can be software corrected after images have been taken, reducing distortion at most proximal parts of the image to <3% (5 cm tubes) or <5% (7 cm tubes)
  • Options: automatic tube recognition system, operation of up to six automatic camera system with one handheld to reduce waiting periods of the operator, UV light, ... we are willing to consider any special request

Ready-for-use minirhizotron sets: incl. imaging device of choice incl. all accessories (charger, cables, etc.); handheld incl. software; MR tubes, 50 or 100 cm (incl. aboveground light protection and endcaps); matching soil coring set to install tubes; manual (English)

Five things Required for a minirhizotron study

  • MR imaging device: options see above / get in contact
  • Minirhizotron tubes (MR-T): Acrylic tubes (standard) of various diameters can be purchased, other materials are available upon request. In addition, we can cut MR-T to length. If you like to acquire your MR-T elsewhere, please inform us about the tube dimension (inner, outer diameter) when purchasing a MR camera.
  • Tube refiningIt is recommended to close your minirhizotron tubes on both sides to prevent water, dust and daylight to enter. We can supply (removable) end caps or produce all possible types of permanent seals (bottom only). If installed in non-temperate ecosystems, an extra insulation of the protruding MR-T part is recommended to minimize changes in soil temperature around tubes. Machine-readable tags glued to each tube can be used by certain devices for automatic tube detection.
  • Soil coring setTo install the MR tubes in situ, a soil corer with a slightly smaller diameter is needed for tight installation. We can manufacture soil corer sets suitable to install the chosen MR-T type to a depth of approx. 1 m (depending on brawn ;) and soil skeleton of course). We currently do not offer mechanized/tractor-mountable drilling devices for deeper installation of MR tubes.
  • Image analyses software: see below for some (free) options.

Selected software tools to analyse minirhizotron Pictures

Visit the great Plant Image Analysis webpage of G. Lobet for a comprehensive list of image analysis software tools.

Vienna Scientific Instruments is not responsible for the content of external links. 

Selected readings on Minirhizotrons

  • Britschgi, D., P. Stamp, and J. M. Herrera. 2013. Root Growth of Neighboring Maize and Weeds Studied with Minirhizotrons. Weed Science 61:319-327.
  • Iversen, C. M., M. T. Murphy, M. F. Allen, J. Childs, D. M. Eissenstat, E. a. Lilleskov, T. M. Sarjala, V. L. Sloan, and P. F. Sullivan. 2011. Advancing the use of minirhizotrons in wetlands. Plant and Soil 352:23-39.
  • McCormack, L. M., D. M. Eissenstat, A. M. Prasad, and E. A. Smithwick. 2013. Regional scale patterns of fine root lifespan and turnover under current and future climate. Global Change Biology 19:1697-1708.
  • Milchunas, D. G. 2012. Biases and Errors Associated with Different Root Production Methods and Their Effects on Field Estimates of Belowground Net Primary Production Measuring Roots. Pages 303-339 in S. Mancuso, editor. Measuring roots - An updated approach. Springer Berlin Heidelberg.
  • Pinno, B. D., S. D. Wilson, D. F. Steinaker, K. C. J. Van Rees, and S. A. McDonald. 2010. Fine root dynamics of trembling aspen in boreal forest and aspen parkland in central Canada. Annals of Forest Science 67.
  • Rewald, B., and J. E. Ephrath. 2013. Minirhizotron techniques. Pages 1-15 in A. Eshel and T. Beeckman, editors. Plant roots: The hidden half. CRC Press, New York, USA.
  • Zeng, G., S. T. Birchfield, and C. E. Wells. 2010. Rapid automated detection of roots in minirhizotron images. Machine Vision and Applications 21:309-317.