Morphological variability of Sorbus domestica L. fruits and seeds in the Mediterranean part of Croatia

Service tree (Sorbus domestica L.) is a wild fruit species that grows in forests and agricultural lands in the Mediterranean and continental region of the Republic of Croatia. This research discusses the morphological variability of service tree fruits and seeds in the Mediterranean part of Croatia. Fruits were collected from natural populations in two different ecological areas: the coastal area (island of Šipan) and the hinterland (Katuni). The morphological characterization of service tree fruits (weight, shape, skin colour, and flesh colour) and seeds (shape and number of seeds fruit^‑1) was carried out using service tree descriptors and the data analysed to define intra-population and inter-population variability. In the coastal area, fruit weight varied from 3.00 to 25.05 g. Considering fruit shape, five shapes of fruit were found; mainly globose, flat spheroidal or conic, and only sporadically pyriform or ovate. The yellow-red flushed fruit skin colour and white-yellow flesh colour prevailed. The number of seeds fruit^‑1 varied between one and three, and the semi-circular shape predominated. Double seeds were recorded for 11% of the accessions. In the hinterland, fruit weight varied from 3.97 to 16.28 g. Three fruit shapes were recorded: mainly globose and sometimes ovate or conic. Yellow fruit skin and white flesh colour prevailed. The number of seeds fruit^‑1 varied from one to four and the semi-circular shape of seeds predominated. Most accessions (67%) within the population contained double seeds. In order to preserve genetic resources and select the best accessions of service trees, it is recommended that future studies should include a wider sampling of service tree populations in the Mediterranean part of Croatia, and investigations of their phenotype and genotype.