Gibberellin Treatment Impacts Fruit Shape in the <i>Pyrus Communis</i> Cultivar “Conference” Through Increased Retention of Apical Fruit

The <i>Pyrus communis</i> cultivar “Conference” is one of the most prevalent pear cultivars in Europe with widespread cultivation that is mainly situated in Belgium, the Netherlands, and the UK. However, a notable issue with this cultivar is the frequent appearance of deformed pears, commonly described as “bottle-shaped”, characterized by extreme elongation. These deformed pears have a significantly reduced market value, resulting in important economic losses. The cause of this deformation has long been attributed to the use of gibberellin treatments, which are used to increase fruit set in this cultivar. However, so far, a true causative link between gibberellin treatments and pear fruit deformation has not yet been established. In this study, we investigated the association between gibberellin treatment and fruit shape deformation for the cultivars “Conference” and “Doyenné du Comice”, taking into account the position of the flower in the cluster (apical vs lateral). The results revealed that gibberellin treatments indirectly affect fruit shape by stimulating the retention of apical pears, which have a natural tendency to grow in an elongated way, resulting in a higher proportion of misshapen pears in the cultivar “Conference”.