Quince (Cydonia oblonga Miller.) belongs to the Rosaceae family and is generally used for fresh consumption and processed items. In this research, fruit characteristics of eight quince genotypes from Iran were investigated via genotype by trait interactions (GTI) biplot. Results indicated that the first two principal components analysis (PC1 and PC2) were used to create a two-dimensional GTI biplot that accounted percentages of 31% and 22%, respectively, of sums of squares of the GTI. The vertex genotypes in polygon were Svs1, Esf, Nb1, Kud2 and Et1; and Svs1 was the winning genotype for pectin, fruit length, phosphorus percent and fruit hardness while Esf was the best genotype for iron percent, fruit diameter, fruit weight and end hold. There were positive correlation among pectin, fruit length, fruit hardness and phosphorus percent as well as among zinc percent, branch length, fruit apparent specific weight, calcium percent and potassium percent. Genotype Svs1 was more desirable followed by genotypes Nb4, Esf and Et1 based on ideal entry biplot and pectin and fruit length were the best traits according to ideal tester biplot. The best genotype for obtaining of high fruit weight was Esf following to Nb4, Svs1 and Nb1 and ranking traits based on fruit weight showed that fruit diameter is more important followed by end hold and iron percent. This study showed that there was relatively high level of variation in quince genotypes grown and morphological traits used in this research indicating that they can be used for characterization and diversity analysis of quince. We concluded from this study that it is imperative for breeders to pay more attention to improve quince morphological traits coordinated to fruit yield performance.
