Morphological and pomological characterizations of olive (Olea europaea L.) cultivars

Olive (Olea europaea L.) is an important agricultural crop with significant economic and ecological value. Olive cultivars vary in morphological and pomological traits, which affect their adaptability and productivity. Understanding these traits is essential for enhancing olive cultivation, supporting breeding programs, and conserving genetic diversity. This study examines the morphological and pomological characteristics of 10 olive cultivars grown in Iran, aiming to characterize their diversity. Significant morphological and pomological variation was found among the 10 olive studied cultivars. Leaf length ranged from 49.07 to 76.57 mm, and leaf width varied from 7.80 to 14.91 mm. Petiole length ranged from 3.86 to 6.74 mm, and petiole diameter varied from 0.59 to 1.07 mm. Fruit length ranged from 16.50 to 32.68 mm, and fruit diameter from 13.58 to 23.80 mm. Fruit weight varied from 2.03 to 9.73 g. Stone characteristics varied, with stone length from 12.00 to 23.44 mm, stone diameter from 6.62 to 11.31 mm, and stone weight from 0.32 to 1.37 g. The coefficient of variation (CV) indicated high variability, especially for fruit density (75.00%), stone color (53.92%), and fruit flesh firmness (46.62%), indicating considerable diversity in these traits. Fruit weight had a CV of 41.20%. ANOVA showed significant differences (p < 0.05) among cultivars for 74.29% of traits, emphasizing morphological and pomological diversity. The two-dimensional biplot created using the first two components (PC1 = 45.29% and PC2 = 20.68%) represented a total of 65.97% of the variation. Positive correlations were observed between fruit length and fruit diameter (r = 0.816**), and between fruit diameter and fruit weight (r = 0.976**). Multiple regression analysis (MRA) found that fruit diameter (β = 1.13, p < 0.00) had a positive correlation with fruit weight, while stone diameter (β = 0.78, p < 0.00) showed a positive correlation with stone weight. Finally, heat map analysis (HMA) clustered the cultivars based on key traits, offering insights into their relationships. This study highlights the importance of specific morphological and pomological traits for differentiating olive cultivars. The findings provided useful insights for cultivar selection, breeding programs, and improving olive productivity. This research also contributes to conserving local olive genetic resources and offers practical guidance for growers in Iran and similar regions.