Use of Dyes to Facilitate Measurement of New Root Growth of Apple

Abstract

The root systems of dormant l-year-old apple (Malus domestics Borkh. `Starkrimson') grafted on seedling rootstock were dipped for 15 seconds in one of six dye treatments or a water control. Trees were destructively harvested at 15, 30, and 90 days after treatment to monitor new root and shoot growth and effectiveness of dyes for distinguishing between regenerated roots and those present at planting. Neutral red and methylene blue allowed effective separation of new and old roots through 90 days after treatment, and had few adverse effects on root or shoot growth, with a water control being the standard. Crystal violet and safranin-O allowed effective separation between regenerated and previously existing roots, but these dyes adversely affected new root and shoot growth. Alizarin red S and Hantover meat branding ink were ineffective for distinguishing between regenerated and previously existing roots by 15 days after treatment.