Pruning type and tree growth control methods influence apple yield and fruit quality

The study was performed with apple cultivar 'Rubin' grafted onto dwarf 'P60' rootstock at the experimental orchard of the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, between 2016 and 2020. The orchard was planted in 2010. Planting distances were 1.25x3.5 m. Seven treatments of tree vigour control were established, including combinations of mechanical pruning, tree trunk incision and application of prohexadione-calcium (Pro-Ca). The strongest growth was recorded for the control treatment, where slender spindle trees were maintained manually. Significantly, the shortest shoots grew where mechanical pruning was applied. A tendency for higher yield was recorded for mechanical pruning treatments. Trunk incision and summer pruning exhibited significantly lower fruit mean weight and diameter. Multiple applications of Pro-Ca increased fruit weight. Less colored fruits were obtained for mechanical pruning treatments.