Staining roots to determine root growth potential of Pinus taeda

Abstract

Root growth potential (RGP) consists of two components: elongation of existing roots and initiation of new roots. Currently, RGP is determined on planting stock from which any “white roots” present at the start of the test are removed. This study compared RGP defined with an alternative staining technique for root marking and also determined the impact of staining on seedling performance after planting in the field. Staining of roots with neutral red, safranin-O, or methylene blue allowed for easy identification of the new roots during indoor root growth potential studies or field experiments. Roots are marked best by dipping in a 1% water solution of methylene blue for 15 seconds, removal of excess stain by placing roots within moist paper towels for 10 minutes, and then rinsing under running water for 1 minute. Results obtained using a stain to initially mark roots prior to RGP tests indicate that measurements of roots using the destructive method may result in an underestimation of new root growth.