Apple rootstock reaction to soil compaction

Container-grown apple trees on a range of rootstocks were exposed to different levels of soil compaction created by changing soil bulk density. In 1998, with soil bulk densities of 1.0, 1.2 and 1.4 g/cm(3) there was no interaction of rootstock and soil compaction for shoot growth of Melrose trees on 9 rootstocks: M.27EMLA, M.9EMLA, M.26EMLA, M.7EMLA, B.9, B.118, G.30, MM.106EMLA, MM.111EMLA. In fact, trees grown in a soil bulk density of 1.2 g/cm(3) had a greater dry weight than trees in 1.0 or 1.4 bulk density soil. However in 1999, with soil bulk densities of 1.0 and 1.5g/cm(3), a significant interaction in shoot growth did occur with 6 rootstocks. Shoot length of trees on M.9EMLA, G.16 and G.30 were less influenced by compacted soil than M.7EMLA, M.26 EMLA and MM.106EMLA. A bulk density of 1.5 caused a decrease in dry weight of shoots, leaves and roots of trees on all rootstocks. Trees on M.26 EMLA and MM.106 EMLA were more affected by severe soil compaction than the other rootstocks. Compacted soil resulted in a decrease in leaf concentration of K and B and an increase in Mg and Mn.