Effect of Root Pruning at Different Growth Stages on Growth and Fruiting of Apple Trees

Abstract

Abstract Three- and 4-year-old ‘MeIrose’/M.7A apple trees were root-pruned on two sides, 50 cm from the trunk, at a depth of 35–40 cm at one of the following growth stages: dormant, full bloom, June drop, and preharvest. Root pruning at dormant or full bloom growth stages reduced trunk cross-sectional area increase and shoot length, reduced average leaf size and fruit size, and increased yield efficiency. Dormant root pruning increased the level of Ca in the fruit flesh. Root pruning at June drop and preharvest had no influence on shoot growth, but increased preharvest fruit drop. Root pruning at full bloom or later increased fruit soluble solids. Considerable root regeneration in close proximity to the cut was evident in November on trees root pruned at the dormant and full-bloom stages. Root regeneration was less on roots pruned at June drop and minimal in preharvest-treated trees. Leaf mineral nutrient levels were not influenced by root pruning treatment. Vegetative growth and fruit size were reduced less by root pruning in the 3-year-old trees than in the 4-year-old trees.