Flat-Bed Scanner Rhizotrons for Demonstrating Root Development As a Classroom Lab Experience.

Teaching root growth and development are important aspects of a crop physiology class, but demonstrating the affects of fertilizer placement and amount on root growth is difficult to demonstrate.  A simple rhizotron that uses flat-bed scanners to take images of roots as they grow is an inexpensive and simple way to demonstrate root growth and involve students in a laboratory setting.  Students constructed the rhizotrons by using flat-bed scanners, garbage cans, and a laptop computer.  The flat-bed scanners were sealed with silicon caulk and placed in the garbage cans, and the rhizotron was filled with sieved soil (Ririe Silt Loam).  Crops grown in the rhizotrons were corn, wheat, and soybeans.  Treatments included amount, type (nitrogen and phosphorus), and placement (incorporated, broadcast, and banded) of fertilizer.  Crops were allowed to grow for three weeks and students scanned the roots and observed above ground growth every 12 hr.  The resolution of the scans was 600 – 1200 dpi.  Fertilizer treatments had faster root growth than control treatments.  Crop roots with ammonium-based fertilizer placed with seed, turned brown and did not grow, whereas roots with fertilizer placed below and to the side grew better.  As part of the students’ final lab report, they had to compile their observations and describe what they learned based on the different treatments.  The students created time-lapse videos using the scanned root images and posted the videos on YouTube.  Students’ reports were graded on proper scientific paper format and their understanding of how the different treatments affected root growth.  Students’ responses to the rhizotron lab experience were very positive with comments such as “I learned a lot about root growth and had fun doing it.”  The flat-bed scanner rhizotron set up is simple and easy, and the laboratory experience provided students with hands-on learning.