The Bigger, the Better: Genetic and Phenotypic Analysis of Fruit Size in Sweet (<i>Prunus avium</i> L.) and Sour Cherry (<i>Prunus cerasus</i> L.) Germplasm

Fruit size and weight are valuable characteristics for cherry breeders, mainly because of their higher market price. Several molecular markers have been developed in recent years and have been correlated with fruit weight. In cherries, <i>FW_G2a</i> was identified as a promising hotspot for fruit size and weight characteristics. Two markers flanking that region were taken into consideration in this study. The local sweet and sour cherry collection in Érd, Hungary, was analyzed using molecular markers to identify possible correlations between the markers and phenotypes. The duration of phenotypic observations varied from 3 years in sour cherry to 5 years in sweet cherry. In our study, we observed correlations between fruit size and weight and the molecular markers of our germplasm collection. We confirmed the previously published association of haplotypes 190–255 and 192–233 with large and small fruit size, respectively, in sweet cherry. Individual alleles of both markers were identified, showing moderate to strong correlations with large and small fruit size in sweet cherry. In tetraploid sour cherry, a higher number of unique allelic combinations were found due to the higher level of ploidy compared to sweet cherry. Individual alleles were detected with moderate positive correlations with fruit size, while one allele showed a strong negative correlation with fruit dimension-related traits. These markers were found to be useful for the characterization of fruit size characteristics, for population selection and for the differentiation of the Hungarian germplasm collection.