EFFECT OF CROP LOAD ON FRUIT QUALITY OF 'FUJI' APPLE

To study the effect of the crop load on fruit quality of the cultivar 'Fuji' apple, in a two-year experiment, fruitlets were hand-thinned to six, eight, ten and in the second year, to twelve fruit per cm(2) of the trunk cross-sectional area (TCSA). With increasing crop load, yield and the proportion of small fruits increased, but mean fruit weight decreased. However, the increase of TCSA and the number of flower clusters at return bloom were the lowest in high cropping trees. The highest percentage of total soluble solids was measured in the lightest cropping trees, which could be in correlation with the highest content levels of the sum of the analysed sugars, sucrose, sorbitol, malic and citric acids in the treatments with lowest crop load in the second year. The most intensive red colour of the fruit and the highest concentration of cyanidin-3-galactoside was observed in the treatment with eight fruit per cm(2) TCSA. Different cropping of trees had no influence on phenolic compounds, such as the concentrations of catechin, epicatechin and chlorogenic acid. On the basis of yield efficiency, return bloom and detected fruit quality parameters cv. 'Fuji' apple has high yield potential.