Effect of Root Pruning on Tree Growth and Fruit Quality of 'Fuji'/M.9 Apple Trees

Abstract

'Fuji'/M.9 apple trees were mechanically root pruned with tractor-mounted root pruner, parallel to the row of 30 cm from the trunk, to the depth of 30 cm, 1) both sides at bud-break stage, 2) both sides at full bloom stage, 3) one side at full bloom stage, 4) one side at fruitlet stage, or 5) untreated as control. Root pruning both sides at bud-break stage or at full bloom stage reduced vegetative growth and yield so much as total shoot length by 54.4% or 58.4% and yield per tree by 75.4% or 70.9%, respectively, compared with controls. However, root-pruning one side parallel to the row at full bloom stage or at fruitlet stage was less affected on vegetative growth than root pruning both sides at bud-break or full bloom stage, not severely reducing fruit growth and yield per tree.