Internal fruit quality depends on the regulation of apple-tree vegetative growth

The effect of tree growth control methods on the accumulation of bioactive compounds in apple fruit was investigated with apple cultivar 'Rubin' on rootstock P 60 at the Institute of Horticulture Lithuanian Research Centre for Agriculture and Forestry in 2015-2018. Tree growth was regulated by prohexadione-calcium, tree trunk incision by chain saw, root pruning and summer pruning. The accumulation of phenolic and triterpenic compounds was investigated. Trunk incision significantly reduced triterpene concentration to 10,853 mg g^‑1 DW, while summer pruning had the opposite effect NDASH apples accumulated significantly higher content of triterpenes (13,727 mg g^‑1 DW). Growth regulator Regalis™ did not have impact on triterpene concentration in apples. Summer pruning significantly increased phenolics in apples (1,905 mg g^‑1 DW), whereas the use of Regalis™ showed a drastic decrease of phenols to 1,307 mg g^‑1 DW.