Fruit quality and bearing potential of chemically thinned 'Braeburn' and 'Camspur' apples

Abstract

The objective of this study was to evaluate the effects of 1-naphtaleneacetic acid (NAA) and 6-benzyladenine (BA) on fruit set, quality and the bearing potential of the apple cultivars 'Braeburn' and 'Camspur'. The chemical rates applied were 6, 8, 10 μl l-1 NAA, 50, 100 and 150 μl l-1 BA to 'Braeburn' and 8, 10, 12 μl l-1 NAA, 50, 100 and 200 μl l-1 BA to 'Camspur'. Both NAA and BA proved to be effective in reducing fruit set in 'Braeburn'. The average fruit weight was increased, while effects of thinning on fruit quality parameters in 'Braeburn' were not consistent. NAA appeared to be more efficient in reducing fruit set in 'Camspur'. NAA advanced maturity of 'Camspur' fruits, while BA was not effective. Both chemicals improved flower bud formation in 'Braeburn' in the second year of the study, but only NAA increased the number of flower buds in 'Camspur'. Thinning with NAA and BA has a potential risk of oversized fruits in 'Braeburn' and abnormally small (pygmy) fruit occurrence in 'Camspur'.