Background: The aim of the present work was to investigate the effect of early leaf removal and cluster thinning treatments in the Mediterranean climate on berry growth and how these two techniques affect phenolic profile (especially proathocyanidins) and color characteristics for later wine production. The study was conducted in 2011 in Podgorica, Montenegro. Two grapevine cultivars were selected to compare different ability in flavonoid accumulation: Vranac, with moderate accumulation and Cabernet Sauvignon, usually showing very good accumulation of polyphenols. Four treatments were compared: only leaf removal, only cluster thinning, leaf removal combined with cluster thinning, and no treatment that was used for control (control set). Results: Early defoliation reduced the yield in both varieties. In Cabernet Sauvignon, defoliation initially delayed berry growth, but at the end, defoliation slightly affected almost all yield parameters (cluster weight, berry weight, and number of berries per cluster), while in cultivar Vranac, defoliation did not modify the berry growth and berry weight. In both varieties, cluster thinning did not affect the berry weight. In the treatments where both defoliation and cluster thinning was applied, a reduction of the cluster weight, berry weight, and berry numbers per cluster was observed. Cabernet Sauvignon showed a greater reactivity to the applied techniques, while Vranac was less reactive. At harvest, no damaged bunches (caused by sunburn) were found in defoliated treatment.

Global viticulture has evolved following market trends, causing loss of cultivar diversity and traditional practices. In Montenegro, modern viticulture co-exists with a traditional viticulture that still maintains ancient practices and exploits local cultivars. As a result, this region provides a unique opportunity to explore processes increasing genetic diversity. To evaluate the diversity of Montenegrin grapevines and the processes involved in their diversification, we collected and analyzed 419 samples in situ across the country (cultivated plants from old orchards and vines growing in the wild), and 57 local varieties preserved in a grapevine collection. We obtained 144 different genetic profiles, more than 100 corresponding to cultivated grapevines, representing a surprising diversity for one of the smallest European countries. Part of this high diversity reflects historical records indicating multiple and intense introduction events from diverse viticultural regions at different times. Another important gene pool includes many autochthonous varieties, some on the edge of extinction, linked in a complex parentage network where two varieties (Razaklija and Kratošija) played a leading role on the generation of indigenous varieties. Finally, analyses of genetic structure unveiled several putative proto-varieties, likely representing the first steps involved in the generation of new cultivars or even secondary domestication events.

Polyphenolic compounds, including total phenolics (TP), total anthocyanins (TA) and total flavan-3-ols (TF3-ols), as well as color intensity (CI) and hue (H), determined by spectrophotometric methods, were studied in Montenegrin red wines from Vitis vinifera L. cv, Vranac. Wines were produced by traditional and modern fermentation methods, applying different oenological products (enzyme, oak chips and grape tannins) during two vintages, i.e. 2008 and 2009. Wines produced from the 2009 vintage presented a slightly higher average amount of total phenols (2,878 mg/l) compared to the wines from the 2008 vintage (2,570 mg/l), and similar contents of anthocyanins and flavan-3-ols. The use of modern fermentation tanks (Sifa and Ganimede) followed by the addition of enzymes, oak chips and grape tannins resulted in a higher amount of polyphenolic compounds. Principal components analysis allowed for the grouping of wines according to the vintage and maceration method.

The influence of three different commercial yeasts (BDX, BM4X4 and ICV D21), on quality parameters of wines from varieties Vranac and Kratošija were studied during two consecutive vintage years. The basic quality parameters of grape must (sugar content, total acidity, pH, tartaric and malic acid) and the wine quality parameters (alcohol content, total dry extract, glycerol, pH, total polyphenols and total anthocyanins) were determined after each phase of vinifications: after alcoholic and malolactic fermentation as well as after three months of wine maturation. There are significant differences in quality parameters of grapes and wines between vintages 2012 and 2013. Higher content of total dry extract and glycerol in wines after completion of alcoholic fermentation was achieved in vintage 2013. In vintage 2013, the highest content of total polyphenols (3.75 and 2.98 g L -1 ) and anthocyanins (1247 and 713 mg L -1 ) in Vranac wine after malolactic fermentation and after three months of maturation, were achieved by yeast BM4X4, while the highest total polyphenols (2.14 and 1.92 g L -1 ) and anthocyanins content (527 and 262 mg L -1 , respectively) was achieved by BDX strain in Kratošija wine. The results of sensory analysis showed no significant differences between the used yeast strains and studied. Surprisingly, the wines of vintage 2012 are even slightly better sensory evaluated.

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