Comprehensive evaluation of oil quality of 98 olive germplasms at 3 maturity levels from the Bailong River Valley area in Longnan, China

To efficiently utilize the olive germplasm resources in the Bailong River Valley region of Longnan, China, the oil content of fresh fruits from 98 olive germplasm samples and three maturity stages (Ⅰ, Ⅱ, Ⅲ) was determined and analyzed. Additionally, 13 oil-related traits were studied using variation, correlation, cluster, and principal component analyses (PCA), aiming to screen excellent germplasm resources through comprehensive evaluation. The results showed that the oil content of fresh fruits exhibits a wide range and increases with maturity: I: 28.00% ~ 60.20%; II: 32.50% ~ 64.60%; III: 34.10% ~ 64.80%. Oleic acid (C18:1) was the predominant fatty acid, and 'Grisha' exhibited the highest content across all three maturity stages. In terms of genetic variation, the coefficients of variation for 13 traits across 98 olive germplasm resources exhibited significant variability. PCA reduced the 13 traits to five principal components, which collectively accounted for a cumulative contribution rate of 77.87%. The comprehensive evaluation has identified the top five olive germplasm resources across three maturity stages, including 'K2', 'Agiou orous', 'FS17', among others. Cluster analysis classified germplasms into three distinct categories (Group I, II, III). Group I is recommended as core germplasm resources suitable for bulk commodity oil production. Group II represents ideal material for cultivating highly stable specialty oils and fats. Meanwhile, Group III offers valuable resources for developing hypoglycemic and lipid-lowering functional oils. This study establishes a foundation for olive breeding, cultivation promotion, and processing in Longnan, China.