Aim of study: One of the newly introduced olive varieties in Montenegro is the Spanish olive (Olea europaea L.) variety ‘Arbequina’. The aim of this work was to study the changes in the reproductive physiology of the cultivar 'Arbequina' in conditions of Montenegro. Area of study: Comparative experimental plots were established in two areas in Montenegro, the coastal region of Ulcinj and the inland region of Podgorica. Material and methods: The research was conducted at four experimental sites (UL1 and UL2 in Ulcinj; PG1 and PG2, in Podgorica) over four years. Flowering phenophases, inflorescence characteristics, and inflorescence architecture were assessed. Pollination trials consisted of open-pollination, self-pollination, and cross-pollination of ‘Arbequina’ with several olive varieties, resulting in an assessment of fruit set. Main results: A high level of fruit set (6.75%) in ‘Arbequina’ in open-pollination was recorded in the multi-varietal orchard (PG2). A much lower fruit set was found in the mono-varietal hedgerow orchards (0.75% in PG1 and 0.33% in UL2). The fruit set was very low in the mono-varietal orchards in self-pollination trials, ranging from 0.01% (PG1) to 0.06% (UL1). Research highlights: These results confirm that ‘Arbequina’ is a self-incompatible variety, which is crucial both for farmers in establishing new plantations and for scientists in future research. Some of the 11 olive varieties cross-pollinated with the ‘Arbequina’ variety displayed pollinating potential, which needs to be proven with paternity tests. Despite the differences between experimental sites and areas, ‘Arbequina’ exhibited high reproductive potential, confirmed by many perfect flowers.

Žutica, the major variety on Montenegrin Coast, belongs to the gro­­up of olive varieties for oil production, with oil content in average above 21%. During the research of the properties of Žutica variety, the existence of variability in the oil content was recorded. In order to determine the degree of the variability of oil content within this variety, the fruits of 42 accessions were analyzed. The results confirmed high content of oil as well as the existence of variability of this parameter between the studied accessions. Twenty two accessions had the content of oil of over 20%, while 13 accessions had the oil content greater than 22% in fresh matter. The highest oil content was in fruit of VAL2 (24.3%) and in dry matter in DUB (63.77%). The results suggest Žutica accessions (clones) with higher oil content promising for spread in the new plantations.

This study analyzed the morphological traits of the Žutica olive variety, assessing its variability through statistical methods. Principal component analysis (PCA) identified the first three components as having the greatest influence on the grouping of Žutica clones. Fruit and endocarp length, width, and weight, as well as pulp weight, were associated with PC1, while the shape index of both fruit and endocarp was linked to PC2. PC3 included the leaf shape index, internode length, pulp percentage, and the pulp/endocarp ratio. Multidimensional Scaling (MDS) and the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) showed that the twenty-three olive clones formed two distinct clusters, with five clones remaining independent. These findings highlight the morphological diversity of Montenegro's oldest olive variety and contribute valuable insights for the preservation and characterization of this important genetic resource.