•Leaf removal and reflective mulch impact on red wines: Merlot, Teran and Plavac mali.•Leaf removal had the strongest influence on phenolic composition of wines.•Reflective mulch treatment had the ...least effect on phenolic composition of wines.•Total phenols, anthocyanins and flavan-3-ols contents exhibited strong correlation with antioxidant activity.
Two years study was conducted to evaluate if leaf removal and red geotextile reflective mulch affect phenolic composition of wines from three red wine grape cultivars, Merlot, Teran and Plavac mali (Vitis vinifera L.). Leaf removal (LR) and reflective mulch (RM), made from weave of aluminum platelets protected by a transparent film and sewn together with red polypropylene threads, were tested separately and combined (LR+RM) on vines of Merlot, Teran and Plavac mali in 2009 and 2010 years, and compared with untreated control. All treatments were applied at veraison. LR had the strongest influence on phenolic composition of experimental wines, particularly in terms of increasing gallic acid, catechin, malvidin-3-glucoside, delphinidin-3-glucoside and peonidin-3-glucoside content. LR+RM resulted in higher gallic acid and malvidin-3-glucoside concentrations. RM treatment had the least effect on phenolic composition of wines but still affected higher epicatechin and gallic acid content. The total phenols, anthocyanins and flavan-3-ols contents in wines exhibited strong correlation with antioxidant activity.
Four red grape cultivars were investigated in order to study the effect of grape harvesting date (ripening stage of the grape) on traditional indicators of maturity such as soluble solids and ...titratable acidity content, as well as on their total polyphenols and total anthocyanins content. Grape varieties grown in different coastal vinegrowing regions, at three different harvesting dates, and from two consecutive vintages, were examined. The results showed uncertainty of traditional indicators of maturity as the only parameter for harvest date determination, since the maximum concentration of soluble solids didn’t correlated with maximum concentration of total polyphenols and anthocyanins in the most of harvest dates. Furthermore, grapes from the third harvest date mostly didn’t have consistently higher polyphenols and anthocyanins levels, so the harvest should not be postponed unduly.
•Microclimatic measurements can explain the specific conditions under which grapes ripen•Cooler climatic conditions during grape ripening improved leaf removal efficiency•Vintage and modifications of ...the canopy microclimate affected the content of important phenols•Control berries experienced higher resveratrol content in a season with more rainfall
Leaf removal in the cluster zone is one of the commonly applied viticultural practices used to increase light penetration and to decrease humidity in dense foliage. A two- year study (2018/2019) was carried out on the Merlot variety grown in the vineyard on the Croatian hillside with continental climatic conditions, to study the effects of basal leaf removal on canopy microclimate, grape chemical composition and vine production. Leaf and lateral shoot removal was performed at berry set. Meteorological data were recorded together with microclimatic measurements: air temperature, UV radiation and relative humidity in the fruiting zone. Leaf removal altered microclimate by increasing the UV radiation within the cluster zone. Sugar concentration, bud fruitfulness and yield performance was not affect by the treatment, while leaf removal significantly reduced the concentration of titratable acidity in berry samples and increased the concentration of phenols, anthocyanins, flavonols and flavan-3-ols in berry skin. Leaf removal had a higher influence on the grape anthocyanin and flavonol composition in a season with the cooler berry ripening conditions. These results revealed important difference in leaf removal efficiency on phenolic composition of the grapes in different seasonal climatic conditions during ripening.
The aim of this work was to classifie vine growing regions of Croatia using bioclimatic indices. For the analysis of climatic conditions, linear trends of bioclimatic indices were determined using ...meteorological observations for all avaliable climatological stations located in vine growing regions of Croatia. Analysis were performed for two different climatological periods: 1961-1990 and 1988-2017. Four commonly used bioclimatic indices were determined: the Winkler index, the Huglin index, Cool night index and Growing season average temperature.
During the ripening process of grapes, the grapevine leaves are the most active green organs that are important for photosynthesis, which is closely linked to the development and metabolism of the ...plant. The detection of plant pigments and phenolic compounds in grapevine leaves can be a good indicator of the ageing process, vine vigor and the plant's ability to respond to fungal attack. In a one-year study, the development of leaf chlorophylls, carotenoids and phenolic compounds during the ripening of six indigenous Croatian grape cultivars and the international cultivars Merlot and Chardonnay was investigated. The chlorophyll a/b ratio and total chlorophyll and total carotenoid concentrations were also investigated. PCA was used to highlight relevant information from the data with the aim of distinguishing individual compounds based on the cultivar and phenological stage. The leaf total hydroxycinnamic acid and flavan-3-ol concentrations decreased slowly during grape development, with the highest concentration immediately after flowering and the lowest during grape ripening. The concentrations of β-carotene, lutein and xanthophylls tended to decrease during bunch closure or veraison, while the concentration of chlorophylls a and b peaked during veraison and then decreased during grape ripening. This research will provide an opportunity to select cultivars with the physiological adaptation to synthesize secondary metabolites that are important for managing stress conditions.
The practical application of grape quality zoning and selective harvesting in small vineyards (<1 ha) has not yet gained much importance worldwide. However, winegrowers with small vineyards are ...looking for ways to improve wine quality and maximise profit. Therefore, the aim of this study was to identify the most predictive vegetation index for grape quality zoning among three vegetation indices—NDVI, NDRE, and OSAVI—at three grapevine growth stages for the efficient use in small vineyards for the selective harvesting and production of different wine types from the same vineyard. Multispectral images were used to delineate two vigour zones at three different growth stages. The target vines were sampled, and the most predictive vegetation index was determined by overlapping the quality and vigour structures for each site and year. A differential economic analysis was performed, considering only the costs and revenues associated with grape quality zoning. The results show that OSAVI is the least predictive, while NDVI and NDRE are useful for grape quality zoning and selective harvesting. Multi-year monitoring is required to determine the ideal growth stage for image acquisition. The use of grape quality zoning and selective harvesting can be economically efficient for small wineries producing two different “super-premium” wines from the same vineyard.
The aim of this study was to assess the influence of the application of mycorrhizal fungal inoculum on “Cabernet Sauvignon” (Vitis vinifera L.) leaf gas exchange, yield parameters, as well as grape ...berry composition, especially regarding phenolic compounds. The experiment was conducted over two years under natural vineyard conditions of the Zagreb wine-growing area, the continental region of Croatia. “Cabernet Sauvignon” grapevines were grafted on SO4 rootstock, both being commonly used in all wine production areas in Croatia. Results obtained demonstrated that symbiotic grapevines, in general, expressed improved leaf gas exchange parameters and higher yield parameters, especially regarding the number of clusters per vine. It should be emphasized that mycorrhizal fungi affected higher total flavan-3-ols, total anthocyanins, and total polyphenols in berry skin in both experimental years. Despite variation in some yield parameters, generally, it is possible to obtain higher yields together with the improved phenolic composition of grapes.
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