Volume Displacement Provides a Quick and Accurate Way To Quantify New Root Production

Root growth potential (RGP) measurement can be time­ consuming and tedious, especially when seedlings have fibrous root systems. A volume-displacement technique involving suspending seedling roots and shoots in a clear plastic tube allows rapid estimation of the volume of plant parts while minimizing gravimetric errors. The technique was tested in three experiments examining (1) the repeat­ ability of the technique, (2) its usefulness in estimating RGP, and (3) the relationship ofvolume displacement to tissue dry weight. Results indicate that this technique provides a quick, reproducible measure ofseedling size while allowing a rapid (2-seedlings-per-minute) assay ofRGP in container-grown stock. Tree Planters' Notes 45(3): 121-124; 1994.