An evaluation of inexpensive methods for root image acquisition when using rhizotrons

Area of Science:

• Plant Science
• Ecology
• Agroforestry

Background:

• Belowground processes are vital for nutrient cycling and global carbon budgets.
• Accurate quantification of fine root growth is essential for understanding ecosystem dynamics and predicting climate change impacts.
• Observing root system growth in natural soil environments presents methodological challenges.

Purpose of the Study:

• To compare the effectiveness of five inexpensive root image acquisition technologies for measuring root elongation rate (RER).
• To evaluate the suitability of these methods for use in natural soil environments within agroforestry systems.

Main Methods:

• Comparison of five root image acquisition methods: flatbed scanner, handheld scanner, manual tracing, smartphone application scanner, and time-lapse camera.
• Measurement of root elongation rate (RER) over three months for hybrid walnut roots in rhizotrons.
• Analysis of image quality, ease of field use, and accuracy of root length and diameter measurements.

Main Results:

• No significant differences were found in relative cumulative root length among the five methods.
• Time-lapse camera and manual tracing overestimated root diameter compared to scanning methods.
• The smartphone scanning application demonstrated the best overall performance regarding image quality and field usability.
• The time-lapse camera provided valuable, automated RER measurements over extended periods.

Conclusions:

• Inexpensive scanning and automated methods accurately measure root elongation and length.
• Time-lapse cameras are effective for RER but not root diameter.
• These methods can detect fine roots down to 0.1 mm in diameter, offering flexible options for researchers based on data needs.