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A study on the influence of planting distances on the growth, productivity and fruit quality of dwarf apple trees in a 15- to 18-year-old orchard was carried out at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Trees of the apple (Malus × domestica Borkh) cultivar 'Auksis' on rootstock P 60 were planted at distances of 3 × 1.5, 3 × 1.25, 3 × 1.00 m and 3 × 0.75 m. With increasing density of fruit trees, singletree growth, generative development and yield were significantly reduced. The opposite results were obtained when these parameters were evaluated per unit area. Yield and fruit quality measurements were made at two canopy heights: 0-1.5 and 1.5-2.5 m. In the upper part of the fruit tree canopy, fruit average weight and diameter were higher, while the colour was more intense and less dependent on the planting density of fruit trees. In the lower part of the canopy, fruit quality was inferior and with increasing fruit tree density it further deteriorated. Planting distances had a significant effect on the accumulation of sugar, soluble solids and dry matter content: greater planting distances resulted in increased sugar content from 10.97% to 11.90%, soluble solids - from 12.30% to 13.17% and dry matter content - from 13.80% to 14.80%. Conversely, higher accumulation of phenolic and triterpenic compounds in apple fruits was found with decreasing planting distances. A significant increase of phenolic compounds from 2.91 up to 4.03 mg g-1 DW (dry weight) was recorded at the upper part of the canopy, while an increase of triterpens from 12.9 up to 16.07 mg g-1 DW - at the lower part of the canopy. The best productivity and fruit quality of 'Auksis' apple trees on P 60 rootstock at the full bearing stage were obtained, when fruit trees had been spaced at 3 × 1.25 m. [ABSTRACT FROM AUTHOR]

Modern apple orchard systems should guarantee homogeneity of fruit internal and external qualities and fruit maturity parameters. However, when orchards reach productive age, a variation of these parameters takes place and mostly it is related to uneven light distribution within the tree canopy. The aim of the study was to evaluate the canopy position's effect on fruit internal and external quality parameters. This is the first study where all the main fruit quality and maturation parameters were evaluated on the same trees and were related to the light conditions and photosynthetic parameters. Four fruit positions were tested: top of the apple tree, lower inside part of the canopy, and east and west sides of the apple tree. Fruit quality variability was significant for fruit size, blush, colour indices, total sugar content, dry matter concentration, accumulation of secondary metabolites and radical scavenging activity. Fruit position in the canopy did not affect flesh firmness and fruit maturity parameters such as the starch index, Streif index and respiration rate. At the Lithuanian geographical location (55°60′ N), significantly, the highest fruit quality was achieved at the top of the apple tree. The tendency was established that apple fruits from the west side of the canopy have better fruit quality than from the east side and it could be related to better light conditions at the west side of the tree. Inside the canopy, fruits were distinguished only by the higher accumulation of triterpenic compounds and higher content of malic acid. Light is a main factor of fruit quality variation, thus all orchard management practices, including narrow two-dimensional tree canopies and reflecting ground covers which improve light penetration through the tree canopy, should be applied. [ABSTRACT FROM AUTHOR]