The influence of planting density on sugar and organic acid content in apple (Malus domestica Borkh.)

The influence of different planting densities on the contents of sugars (glucose, fructose, sucrose), sorbitol and organic acids (citric, malic, shikimic, fumaric) in cvs. 'Golden Delicious', 'Jonagold', 'Idared', 'Elstar', 'Gloster' and 'Gala must' was studied at the Fruit Growing Centre at Maribor in the year 1998. Cvs. 'Golden Delicious', 'Jonagold', 'Elstar' and 'Gloster' were planted at densities of 6000, 9000 and 18000 trees/ha, cv. 'Idared' at densities of 2500, 6000 and 9000 trees/ha, and cv. 'Gala must' at densities of 2700, 4100 and 8000 trees/ha. The sugars and organic acid contents were determined by High Performance Liquid Chromatography. In cv. 'Jonagold' the planting density influenced the content of fructose. Different planting densities influenced the concentration of fructose in cv. 'Golden Delicious', the content of sucrose in cv. Elstar' and the content of sucrose and soluble solids in cv. 'Gloster'. The planting density of 9000 trees/ha had less fructose and sorbitol than the planting density of 6000 trees/ha in cv. 'Idared'. The content of fructose increased with an increasing planting density in cv. 'Gala must' while the soluble solids content decreased. Different planting densities influenced the organic acids content.