A Time-Lapse Imaging System for Documenting Root Response to Environmental Conditions.

Plant roots normally grow in opaque media, necessitating destructive sampling techniques to determine their response to environmental changes.  Destructive sampling frequently introduces artifacts and increases the variability within treatments.  This results in a significant reduction in precision of measurement that becomes extreme with roots smaller than 0.2 mm diameter.  If the requirement for physical structure is relaxed, plants can be grown in aeroponics or hydroponics, and images taken frequently and non-destructively.  We have developed such a system.  Our aeroponic scanning mesorhizotrons (ASM) consist of a bank of scanners controlled by a single computer.  An individual scanner is modified to be water tight then a 10 mm deep chamber is constructed using the glass-scanning surface as one side.  The chamber is fitted with entrance and exit tubes for aeroponic fog and slits in the rubber sides to place plants in.  The scanner is then oriented at 60 degrees from horizontal.  The aeroponics can be manipulated under computer control to modify any environmental characteristic except physical structure based scenarios.  With ASMs, we have demonstrated a cessation of grass root growth within hours of shoot clipping, and have characterized the developmental patterns of perennial ryegrass root systems.