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During the period 2020-2022, an experiment was conducted in the experimental vineyard of the Agricultural University - Plovdiv, and four clones of the wine variety Syrah, numbered 100, 174, 470 and 524, grafted on the SO4 rootstock were selected as the study object. During the "pea size" phase, the green pruning operation – bunch thinning was applied. The shoots growth starts from the vegetation phase "first leaf appearance" and ends at the "veraison". The average duration is about 100 days, covering the period of May, June and July. It was found that the vine shoots from a clone 470 reached the greatest average length, V3 - 285, 265, 290 cm and V7 - 359, 336, and 380 cm, and those from a clone 100 were distinguished by the weakest growth, V1 - 197, 203 and 205 cm and V5 - 240, 228 and 245 cm. Differences were proven between the variants, both in the non-reduced (V1, V2, V3, and V4) and in those with reduced yields (V5, V6, V7, and V8), as after reducing the number of bunches, the length of the shoots was longer - high in all vines from the used Syrah clones. This study provides information on the relationship between the applied green pruning operation (bunch thinning) during the growing season and its effects on the vegetative growth. Balancing the vines bud load by controlling yield during the growing season is a preferred viticultural practice for increasing the grape quality. [ABSTRACT FROM AUTHOR]

The experiment was conducted in the experimental vineyard of the Agricultural University - Plovdiv, during the period 2020-2022. Two clones of the Syrah variety numbered 174 and 470 grafted onto the SO4 rootstock were used. The green pruning operation 'bunch thinning' was applied, performed manually in the 'pea size' phase. Differences were found in the bunch structure according to the indicators - normal berries (%), bunches (%), milleranded berries (%), raisined berries (%), theoretical yield (%), average bunch mass (g) and average cluster size (cm). The mechanical analysis was obtained from skins (%), seeds (%), mesocarp (%), average weight of 100 berries (g), number of seeds in 100 berries, average seeds weight in 100 berries (g), average berry size (mm). The grape ripening dynamics was monitored, through the quantitative change in the sugar content (%) and titratable acids (g/l). The application of bunch thinning, as a widely known viticultural practice, part of the Canopy management complex of activities involved in, has had a positive impact on accelerating the grapes ripening and increasing its quality in the studied clones. [ABSTRACT FROM AUTHOR]

Wine is a product obtained through fermentation process, the trans-resveratrol is a polyphenol derived from grapes and a natural antioxidant that passes into wine. The trans-resveratrol is a rare compound with the highest content in the red wine and a positive physiological effect on human organism. The present study was conducted in three years period from 2020 until 2022 at the Agricultural university-Plovdiv experimental vineyard, located near the village of Brestnik. Four Syrah wine variety clones were included and eight experimental wines have been made during the experimental period. In all tested wines, the presence of trans-resveratrol was detected but its amount was higher in clone 524 (V4) with non-reduced yield (3.35, 4.36, 7.02 mg/L), and in clone 100 (V5) with reduced yield (5.24, 3.75, 7.23 mg/L). Reducing the bunch numbers at the “pea size” stage did not significantly influence the content of trans-resveratrol. The wine antioxidant properties were directly affected by the clone and the grape harvest and was under the terroir influence. In today's conditions of overproduction and increased competition, the results of this study provide a valuable economic information and expand the portfolio of wineries. [ABSTRACT FROM AUTHOR]

The study compares morphology of clusters and fruits, the chemical composition and changes of pulp in the process of maceration of grape cultivars ‘Mavrud’, ‘Pinot Noir’ and ‘Merlot’. The cultivar ‘Mavrud’ had biggest clusters and fruits. Its fruits were less firm but had the highest acidity while the fruits of the ‘Pinot Noir’ had the highest content of soluble solids and dry matter and the greatest firmness but the lowest acidity and content of nitrites and nitrates. The fruits of the ‘Merlot’ cultivar had the highest content of L-ascorbic acid, nitrites and nitrates. The pulp colour was largely affected by the maceration temperature. During a warm maceration, the process of pulp darkening accelerated and the red colour saturation increased, whereas cold maceration resulted in the blue colour saturation.

As industrial culture the vine is grown successfully between 25–50 ° N and 30–50 ° S. with certain deviations depending on the orographic features of the terrain. Most suitable conditions for the development of the vine there are in moderately warm regions, located between 34–45 ° north latitude. Precisely in this most favorable for development of vine culture zone is located the territory of the Republic of Bulgaria – between 41°14′ and 44°12′ N / Fig. 1 /.