CuCO3-painted Containers and Root Pruning Affect Apple and Green Ash Root Growth and Cytokinin Levels

CuCO 3 at 100 g·liter -1 in a paint carrier applied to interior container surfaces effectively prevented root deformation in container-grown Malus domestica Borkh. and Fraxinus pennsylvanica Marsh. seedlings. CuCO 3 treatments nearly doubled the number of white unsuberized root tips in both species. CuCO 3 treatment increased some measures of root and shoot growth before and after transplanting to larger untreated containers. Root pruning at transplanting tended to reduce root and shoot fresh and dry matter accumulation in F. pennsylvanica seedlings and shoot extension in M. domestica seedlings. In some cases, root pruning of M. domestics at transplanting from CuCO 3 -treated containers increased root growth compared to unpruned CuCO 3 -treated and untreated seedlings. Changes in growth induced by CuCO 3 and root pruning were not related to changes in trans -zeatin riboside-like activity in the xylem sap of-apple.