MODIFYING APPLE SPINDLE TREES TO IMPROVE FRUIT QUALITY

Dwarf and semidwarf apple trees planted at high density orchard are poorly il- luminated when they come into full bearing. Insufficient illumination has adverse effect on apple red blush. Studies were carried out in years 2009-2013 in the Institute of Horti- culture at Skierniewice. The object of the study were 12-year-old apple trees of 'Jonagold' and 'Gala'. Trees were grafted on semi-dwarf M.26 rootstock, planted at 4 × 2 m, trained to the spindle system, had been pruned until the spring of 2009 by the renewal method. Prior to the trial the trees were 3 m of height and 2.5 m in spread. To improve fruit qual- ity, additional four pruning treatments were applied in 2009-2013. They were: 1. Remov- ing the lowest branches up to 1 m above the ground; 2. Heading annual shoots at the tree top and the base of the canopy; 3. Cutting out a slim waist in the middle part of the can- opy; 4. Slimming the tree top; 5. Trees in the standard spindle form treated with renewal pruning served as the control. All the pruning systems ensured high yields. Only the prun- ing to a slim waist and slimming the tree top improved light penetration to the interior part of the tree canopy, fruit size and color. Pruning treatments slimming tree silhouette can solve the problem of poor quality apples in densely planted orchards.