Impact of Progerbalin LG® on the apple fruit physical attributes

Abstract

During two consecutive years (2010 and 2011) we evaluated the impact of Progerbalin LG® (mixture of gibberellins (GA4+7) and N6-benzyladenine) on fruit weight, fruit dimensions, elongation, geometric mean diameter or fruit size, aspect ratio, surface area and fruit volume of five apple cultivars belonging to ‘Red Delicious’ group (‘Hapke’ grafted on M.9 and M.26, ‘Hi Red’, ‘Starking’ and ‘Top Red’ on M.9, and ‘Red Chief Camspur’ on MM.106 rootstock). Trees were sprayed twice with 30, 50 or 100 ml L−1 i.e. between 80 % of open flowers and the following petal fall (first treatment), and 10 days after first application (second treatment); control trees were not sprayed. Results showed that the lowest dose increased fruit weight in all cultivars, except ‘Top Red’ and ‘Red Chief Camspur’; this dose promoted fruit dimensions, fruit size and elongation in ‘Hapke’ on both rootstocks, and also fruit dimensions, surface area and fruit volume in ‘Hi Red’. Regarding ‘Starking’, different doses of Progerbalin LG® did not affect other properties evaluated, but season played an important role in these cases. In contrast, the highest dose of this hormone improved all physical attributes in ‘Top Red’ and ‘Red Chief Camspur’, except elongation and/or aspect ratio. In some cases, good values were found in control treatment.