Probírka indukovaná samostatnými nebo kombinovanými aplikacemi BA, NAA a metamitronu v jabloních odrůdy ‘Golden Delicious’ [Thinning Induced by single or combined applications of BA, NAA and Metamitron in apple Variety ‘Golden Delicious’].

It is usually necessary to utilize some method of fruit set regulation to attain high ratio of fruit with optimal size and market price. Most of the current market cultivars of apple tend to create high flower and fruit set in common years. Chemical thinning is currently the most used and relatively safe method of fruit set regulation. Objective of our trial was to compare efficiency of single or combined applications of available chemical thinners benzyladenine, 1-naphthalene- acetic acid, and metamitron to yield and fruit size in productive orchard of ‘Golden Delicious’. Significant thinning was found in treatments where metamitron was used alone or in combinations. Treatments where benzyladenine and 1-naphthaleneacetic acid were used alone or in mutual combination showed insignificant thinning effect. Treatments with significant thinning efficiency had also significantly higher average fruit weight and lower yield of fruits under 65 mm. We assign low efficiency of benzyladenine and 1-naphthaleneacetic acid to worse weather conditions during application, lower used doses and spraying without added surfactant. Metamitron showed thinning ability, nevertheless, in combined treatments the yield reduction was quite high and thinning in lower part of crown too strong.