Control of Fruit Cracking of Japanese Pear ‘Kosui’ and ‘Niitaka’ using Gibberellin Tape

Abstract

Control of fruit cracking of Japanese pear ‘Kosui’ and ‘Niitaka’ by gibberellin tape was examined, and the mechanism of occurrence of fruit cracking was discussed.
1. Gibberellin tapes were tied at the calyx ends (‘Kosui’ only) or peduncles about one month after full bloom. Gibberellin tape restrained fruit cracking conspicuously. Especially the effect was excellent with the treatment of calyx ends.
2. At the time of harvesting, average fruit weights from gibberellin tape treatments of calyx ends and peduncles were heavier than from non-treatment. No difference appeared in flesh firmness or in refractive index of fruit juice by different treatments.
3. The cell number of the flesh did not increase by gibberellin tape treatments. We can estimate from the results that the treatments maintained a balance of growth of the whole fruit by advancing the enlargement of the fruit apex, and then fruit cracking was restrained.