Inheritance of Calyx Abscission in Apple: A Trait with Potential Impact on Fruit Rot Susceptibility

Fruit rots, both pre- and postharvest, represent a major problem in apple production, leading to significant yield losses each year. In this study, the inheritance of calyx abscission, a trait that could potentially reduce susceptibility to various fruit rots, was investigated in an F₁ population. Calyx persistence rates were phenotyped in the field in 2023 and 2025 on 122 offspring derived from a cross between 'Idared' and <i>Malus baccata</i> 'Jackii', the latter exhibiting complete calyx abscission. QTL analyses were conducted using genotypic data and a genetic linkage map generated in a previous study. Results show, for the first time in apple, that calyx abscission is a heritable trait influenced by multiple loci, with the strongest effects detected on linkage groups 5 and 13. Whether calyx abscission is linked to reduced susceptibility to fruit rots, and for which pathogens this applies, remains to be investigated in future studies.