A B S T R A C TThe objective of this work was to evaluate the yield components and physicochemical characteristics of bunches and berries of new grape varieties for juice elaboration, which were 'Isabel Precoce' (Vitis labrusca L.) and the hybrids 'BRS Carmem', 'BRS Cora' and IAC 138-22 'Máximo' grown onto 'IAC 572' and 'IAC 766' rootstocks under tropical conditions. The yield components (number of bunches and yield per vine, as well as productivity) and the physicochemical characteristics of the bunches and berries of the eight scion-rootstock combinations were evaluated in three seasons. All data were subjected to analysis of variance and principal components analysis. The varieties 'Isabel Precoce', 'BRS Cora' and IAC 138 22 'Máximo' produced high fruit yield, with the number of bunches and yield per vine similar to one another and superior to those of 'BRS Carmem'. Significant differences occurred among varieties in the physicochemical grape characteristics. 'Isabel Precoce' and 'BRS Carmem' grapes had balanced levels of sugar and acid content, and 'BRS Cora' presented large bunches and berries, reaching high soluble solids content despite the high acidity. IAC 138-22 'Máximo' grape also had large bunches but small berries and limited potential in the accumulation of sugars. The 'IAC 766' rootstock resulted in the best performance across all four varieties evaluated, showing maximum results in terms of fruit yield and physicochemical quality attributes of grapes.

This study aimed to assess the effect of rootstocks (IAC 572 and IAC 766) and potassium fertilization at different concentrations (0, 75, 150 and 300 kg•ha -1 K 2 O) on the phenology and thermal demand of the Niagara Rosada grapevine, and to evaluate the development of chemical traits during maturation stage. The length of the main phenological stages was recorded within two production seasons.Total thermal demand was calculated using the degree-day concept. The berries' titratable acidity and soluble solids contents were determined during maturation. Results indicated that IAC 572 and IAC 766 rootstocks along with potassium fertilization had no influence on the phenological cycle or thermal demand of the Niagara Rosada grapevine. The production cycle lasted 144 to 148 days with thermal demands ranging from 1,465.2 to 1,615.1 degree-days. For better grape quality, i.e., with a balance between soluble solids and acidity levels, it is estimated that the grape harvest is carried out around 21 to 24 days after the veraison.

The current study aimed to evaluate the effect of different rootstocks (‘IAC 766’, ‘IAC 572’, ‘IAC 313’, ‘IAC 571-6’ and ‘106-8 Mgt’) on the physicochemical quality of ‘Niagara Rosada’ grape under Brazilian subtropical climate. In this study, a vineyard trellising system supported three years old vines at a density of 6536 plants ha-1. Therefore, evaluations consisted of three pruning seasons: two winter pruning (August 2011 and September 2012) and a summer pruning (January 2012). A complete randomized block design was conducted, subdivided into plots, with five replicates, the plots represented by 5 rootstocks and subplots by pruning seasons. We evaluated bunch number per plant; bunch, berry and rachis fresh mass; berries number per bunch; soluble solid, pH and titratable acidity content in the grape must. Results showed that ‘Niagara Rosada’ grafted onto ‘IAC 572’, presented the highest bunch mass (227g), rachis fresh mass (7.5g) and berries number per bunch (66); while ‘IAC 313’ rootstock performed the lowest values. Moreover, ‘IAC 766’ and ‘106-8 Mgt’ rootstocks presented the highest soluble solid and titratable acidity content, due to these rootstock’s precocity. Furthermore, the highest ratio between soluble solid and titratable acidity was found in ‘Niagara Rosada’ grafted onto ‘IAC 313’ and ‘IAC 571-6’ rootstock.

The objective of this work was to evaluate the productive performance and physicochemical characteristics of the Isabel Precoce, BRS Carmem, BRS Cora, and IAC 138-22 Máximo grape (Vitis labrusca) cultivars for juice grafted onto the 'IAC 572 Jales' and 'IAC 766 Campinas' rootstocks. A randomized complete block design, in a 4×2 factorial arrangement, was used. Productive performance was evaluated through: production per plant; yield; number of clusters per vine; and physical characteristics of clusters, berries, and rachis. The physicochemical characteristics of must composition were also determined through the content of soluble solids, reducing sugars, titratable acidity, maturity index, and pH. Since there was no significant interaction between cultivars and rootstocks for most of the evaluated characteristics, each factor was analyzed separately. The 'IAC 766 Campinas' rootstock provided a higher yield and more suitable physicochemical characteristics for the four cultivars. However, regardless of the rootstock used, cultivars BRS Carmem, IAC 138-22 Máximo, and Isabel Precoce were more productive than BRS Cora.

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