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 Malus baccata ‘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.