Multivariate Analysis of Morphological Variables in Olive ( Olea europaea L.) Cultivars

This study investigates the morphological variation of nine olive (Olea europaea L.) cultivars grown under a single ecological condition. The primary objective was to evaluate phenotypic variability using multivariate analyses and to identify key traits contributing to cultivar discrimination and selection. A total of thirty-two quantitative and qualitative characteristics were assessed over two consecutive years. The results revealed substantial phenotypic variation among cultivars, with fruit nipple shape exhibiting the highest coefficient of variation. Tukey’s multiple comparison tests indicated significant differences among cultivars, with fruit weight ranging from 0.64 (“Mission”) to 3.45 g (“Zard”). Frequency distribution analysis showed that ripening date was earliest in “Mari” and latest in “Koroneiki,” “Manza,” “Mission,” and “Roghani,” while high fruit density was observed in “Dezfooli,” “Golooleh,” “Koroneiki,” “Mari,” and “Mission.” Correlation analysis revealed a strong positive relationship between fruit flesh percentage and fruit flesh thickness. Multiple regression analysis demonstrated that fruit weight was positively associated with fruit flesh weight and stone weight. The first three principal components explained 74.14% of total variation, indicating that fruit size and stone-related traits accounted for most morphological variation. The PCA biplot positioned “Mission,” “Manza,” “Mari,” and “Koroneiki” outside the 95% confidence ellipse, indicating distinct morphological profiles. Overall, fruit weight, flesh thickness, and stone-related traits were identified as key parameters for effective cultivar discrimination. The findings provide valuable insights for olive breeding programs and the conservation of olive genetic resources.