Breeding assessment of the main economic traits of the olive (Olea europaea L.)

The article presents a comprehensive analysis of 40 olive cultivars and hybrid forms bred and introduced by the Nikitsky Botanical Garden. The study examines their yield, oil content in fruits, fruit weight, flesh-to-pit ratio, frost resistance, and timing of the onset of the main phenological phases. The increase in the olive cultivation area in the Mediterranean region as well as beyond the traditional olive production areas is largely driven by the growth of olive oil consumption. This motivates producers to increase olive fruit production. The research aims to identify new genetic sources for breeding and to identify candidates for new cultivars. The study was undertaken in 2022–2024 on ex situ plants of the NBG-NSC collection. The Italian cultivar Corregiolo and the cultivar Nikitskaya Krupnoplodnaya adapted through NBG-NSC breeding were used as a standard in assessing the phenorhythmics and productivity components. The results revealed significant phenotypic variability in morphometric, biochemical, and physiological traits. Using k-means clustering, we categorized genotypes into groups which were identified based on individual traits significant for breeding. These traits are as follows: large fruit size (Nikitskaya Krupnoplodnaya, Tiflisskaya, Ascolano, Santa Caterina, Tolgomskaya, Otur, Manita, Krymchanka, Nikitskaya Zhemchuzhina, Tavrida); high yield (Corregiolo, Nikitskaya Krupnoplodnaya, Nikitskaya, Otur, Tifl isskaya, Ellada, Tavrida, Krymchanka, Agatovaya, Obilnaya, Nikitskaya Zhemchuzhina); high oil content in fruits (Corregiolo, Nikitskaya Krupnoplodnaya, Nikitskaya, Razzo, Otur, Primorskaya, Kolkhoznitsa); a good flesh-to-pit ratio (Piangente, Santa Caterina, Tolgomskaya, Ellada, Konservnaya, and Obilnaya); increased frost resistance (Tossiyskaya, Rannyaya, Tavrida, Ellada, Universalnaya, Krymchanka); early flowering (Lomashenskaya, Pulazeqin, Otur, Nikitskaya Krupnoplodnaya, Tiflisskaya, Tlemcen, Universalnaya, Izyashnaya, Yubileynaya, Rannyaya, Konservnaya, Nikitskaya Zhemchuzhina); early fruit ripening (Dalmatica, Kalinjot, Nikitskaya, Universalnaya, Izyashnaya, Yubileynaya, Oktyabrskaya, Rannyaya, Primorskaya, Konservnaya, Obilnaya, Krymchanka, Nikitskaya Zhemchuzhina, Tavrida, Manita, Ellada). The cultivars were grouped according to a set of the major economic traits in comparison with the cultivar model using hierarchical clustering. The Tossiyskaya, Nikitskaya, Tiflisskaya, Nikitskaya Krupnoplodnaya, Otur, Manita, Ellada, Tavrida, Nikitskaya Zhemchuzhina, Krymchanka, Agatovaya, Obilnaya genotypes showed the closest similarity to the cultivar model.