Influence of fruit thinning chemicals on photosynthetic activity and vitality of apple leaves (Malus domestica Borkh.)

Abstract

The influence of various apple fruit thinning methods on photosynthetic activity and the content of photosynthetic pigments and ascorbic acid in the leaves was investigated. Thinning was implemented manually and with several chemicals (Carbaryl, Terbacyl, NAA, NAAm, BA, Ethephon). The experiment was carried out in 1995 on ‘Jonagold’ and in 1996 on ‘Jonagold’, ‘Elstar’, ‘Golden Delicious’. Cultivars of control trees, on which no thinning was implemented, were used for comparison. Except for the Carbaryl in 1995 and Terbacyl in 1995 and in 1996, which caused a decrease in photosynthesis, thinning had no influence on the content of photosynthetic pigments and ascorbic acid. With respect to these two vitality parameters, we can conclude that the chemicals used have no major effect on apple tree vitality.