The Influence of Apple Tree Chemical Thinning on Yield and Fruit Quality

In the present study, the influence of different agents for apple tree chemical thinning on yield components and fruit quality was investigated. The experiment was conducted in apple orchard established with cultivars 'Idared', 'Golden Delicious' and 'Mondial Gala' during 2009. The agents tested were Napthalenacetamid (NAD), alpha-naphtaleneacetic acid (NAA, two concentrations) and Carbaryl (Sevin WP-50). Chemical thinning expressed significant influence on decreasing of fruit number per tree and increasing of fruit size. Among the tested agents only Carbaryl did not show these effects in 'Golden Delicious'. Yield per tree was not affected by chemical treatments in 'Idared', whereas the thinning significantly decreased the yields in 'Golden Delicious' and 'Mondial Gala'. A significant return bloom was recorded in all chemical treatments in 'Idared' and 'Golden Delicious'. Chemical fruit composition was not influenced by thinning treatments in all tested cultivars. In 'Mondial Gala' more intensive fruit colour was recorded in the treatments with Carbaryl and NAD, which also reduced the fruit number per tree