Hybrid (Vitis vinifera ×Vitis labrusca) table grape cultivars grown in the subtropics often fail to accumulate sufficient anthocyanins to achieve good uniform berry color. Growers of V. vinifera table grapes in temperate regions generally use ethephon and, more recently, (S)-cis-abscisic acid (S-ABA) to overcome this problem. The objective of this study was to determine if S-ABA applications at different timings and concentrations have an effect on anthocyanin regulatory and biosynthetic genes, pigment accumulation, and berry color of the Selection 21 cultivar, a new V. vinifera ×V. labrusca hybrid seedless grape that presents lack of red color when grown in subtropical areas. Applications of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins and of the individual anthocyaninsanthocyanins: delphinidin-3-glucoside, cyanidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside in the berry skin and improved the color attributes of the berries. Treatment with two applications at 7 days after véraison (DAV) and 21 DAV of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins in the skin of berries and increased the gene expression of CHI, F3H, DFR, and UFGT and of the VvMYBA1 and VvMYBA2 transcription factors in the seedless grape cultivar.

Vitis labrusca grapes are widely cultivated in some countries such as Brazil and the United States, especially for juice production. ‘Isabel’ is one of the main cultivars because of its high production and disease tolerance, but the juice is deficient in color. The objective of this study was to evaluate the effect of timing and concentration of (S)-cis-abscisic acid (S-ABA), a specific isomer of abscisic acid applied to ‘Isabel’ grapes, aiming to increase anthocyanin accumulation and to improve juice quality. The trial was conducted on two consecutive seasons (2011 and 2012) in a commercial vineyard located in Maringa, PR, Brazil. The vines were trained in an overhead trellis system and spaced at 4.0 × 1.0 m. The statistical model used was a randomized block design with four replications and five treatments: control; S-ABA at 200 mg·L−1 at 7 days after veraison (DAV); S-ABA at 400 mg·L−1 at 7 DAV; S-ABA at 200 mg·L−1 at 7 DAV + 200 mg·L−1 at 15 days after the first application (DAFA); and S-ABA at 400 mg·L−1 at 7 DAV + 400 mg·L−1 at 15 DAFA. There were no significant differences between treatments in relation to berry or cluster size or weight. S-ABA application resulted in increased anthocyanin concentrations in both berries and juices, mainly when 400 mg·L−1 was applied. Sensory analysis also revealed the efficiency of this plant growth regulator to promote better acceptance of grape juices. Thus, a single application of S-ABA at 400 mg·L−1 at 7 DAV is sufficient to increase the anthocyanins concentration of ‘Isabel’ grapes, improving the acceptance of juice by consumers.

-The objective of this work was to evaluate the effect of (S)-cis-abscisic acid (S-ABA) application at different ripening stages, in increasing phenolic compounds and color of berry and juice of 'Isabel' grape (Vitis labrusca). The evaluated treatments were: control, without S-ABA application; 400 mg L -1 S-ABA applied 7 days before veraison (DBV) + 400 mg L -1 S-ABA at 35 days after first application (DAFA); 400 mg L -1S-ABA applied at veraison (V) + 400 mg L -1 S-ABA at 35 DAFA; and 400 mg L -1 S-ABA applied 7 days after veraison (DAV) + 400 mg L -1 S-ABA at 35 DAFA. There was no difference among treatments regarding the physical characteristics of berries and clusters, as well as total polyphenols in berry and juice. However, there was an increase in total anthocyanins in berry and juice with S-ABA application. Colorimetric variables indicated the increase in color of berry treated with S-ABA. Juices produced from grapes treated with S-ABA were more appreciated by tasters. The treatments with 400 mg L -1 S-ABA applied 7 days before, during, or 7 days after veraison, combined with an additional application 35 days after the first one, increment total anthocyanin concentration and color of berry and juice of 'Isabel' grape, with better juice acceptance, without affecting total polyphenol concentration.Index terms: Vitis labrusca, anthocyanins, color, growth regulador. Cor das bagas e do suco da uva 'Isabel' tratada com ácido abscísico em diferentes fases de maturaçãoResumo -O objetivo deste trabalho foi avaliar o efeito da aplicação do (S)-cis-ácido abscísico (S-ABA) em diferentes fases de maturação, no incremento de compostos fenólicos e na cor das bagas e do suco de uva 'Isabel' (Vitis labrusca). Os tratamentos avaliados foram: testemunha, sem aplicação de S-ABA; 400 mg L -1de S-ABA aplicados 7 dias antes do "véraison" (DAV) + 400 mg L -1 de S-ABA aos 35 dias após a primeira aplicação (DAPA); 400 mg L -1 de S-ABA aplicados no "véraison" (V) + 400 mg L -1 de S-ABA aos 35 DAPA; e 400 mg L -1 de S-ABA aplicados 7 dias após o "véraison" (DAV) + 400 mg L -1 de S-ABA aos 35 DAPA. Não houve diferença entre os tratamentos para as características físicas das bagas e dos cachos, bem como para os compostos fenólicos totais das bagas e do suco. Contudo, houve incremento de antocianinas totais da baga e do suco com a aplicação de S-ABA. As variáveis colorimétricas indicaram aumento da cor das bagas quando estas foram tratadas com S-ABA. Os sucos elaborados com uvas tratadas com S-ABA foram mais apreciados pelos provadores. Os tratamentos com 400 mg L -1 de S-ABA aplicados 7 dias antes, durante ou 7 dias após o "véraison", associados à uma segunda aplicação 35 dias após a primeira, promovem o incremento da concentração de antocianinas totais e da intensidade da cor das bagas e do suco da uva 'Isabel', com melhor aceitação do suco, sem afetar a concentração de polifenóis totais.Termos para indexação: Vitis labrusca, antocianinas, cor, regulador de crescimento.

The objective of this study was to evaluate techniques, such as flower-cluster and berry-cluster thinning at different times, to prevent bunch compactness of 'BRS Vitoria', a new black seedless grape. The experiment was conducted during two consecutive seasons (2013 and 2014) in a commercial vineyard located in Marialva, PR, Brazil. The grapevines were trained in an overhead trellis system, spaced at 2.5 × 5.0 m. The experimental design used was randomized blocks with four replications and six treatments: control (no thinning); flower-cluster thinning or brushing prior to anthesis; and berry-cluster thinning at different times, when berries were 3-6, 7-10, 11-15, or 16-18 mm in diameter. The bunch compactness incidence was evaluated according to the following classification: very loose, medium loose, and very dense bunches. The physicochemical characteristics of bunches and the yield were also evaluated. Data were submitted to analysis of variance, and means were compared using Tukey's test at 5%. Berrycluster thinning when 'BRS Vitoria' berries are between 7 and 18 mm in diameter is efficient for reducing bunch compactness, as it results in a higher incidence of medium loose and a lower incidence of very dense bunches with optimum yield, while flower-cluster thinning or brushing prior to anthesis should be avoided because it promotes higher incidence of very loose bunches with reduced yield.

ResumoA uva 'Isabel', principal cultivar utilizada para a elaboração de suco no Brasil, apresenta deficiência de cor, sendo uma das alternativas, a aplicação do ácido abscísico (S-ABA), visto que o acúmulo de antocianinas, pigmento que interfere na cor das bagas, parece ser regulado, por este fitohormônio. O objetivo do trabalho foi avaliar o efeito de concentrações de S-ABA, aplicadas em épocas distintas nos cachos da videira 'Isabel', na melhoria dos atributos de cor. As videiras foram conduzidas em espaldeira, no espaçamento de 2 x 1 m, em cordão esporonado. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições e cinco tratamentos: Testemunha; S-ABA 200 mg L -1 aplicado sete dias após o veraison (DAV); S-ABA 400 mg L -1 , 7 DAV; S-ABA 200 mg L -1 , 7 DAV + 200 mg L -1 , 10 dias antes da colheita (DAC); e S-ABA 400 mg L -1 , 7 DAV + 400 mg L -1 , 10 DAC. No momento da colheita foram avaliadas as variáveis massa e diâmetro das bagas, massa e comprimento dos cachos, teor de sólidos solúveis (SS), acidez titulável (AT) e índice de maturação (SS/AT). Foi avaliado, também, a concentração de antocianinas e o índice de polifenóis totais do mosto e do suco, elaborado pelo método da panela extratora e a cor das bagas por colorimetria. A aplicação de S-ABA não influenciou as características físicas das uvas, entretanto, propiciou o aumento no teor de SS e a relação SS/AT das bagas, exceto para a concentração de 200 mg L -1 aplicada sete dias após o veraison. O S-ABA exerce efeito sobre a melhoria no teor de antocianinas das bagas e do suco da uva 'Isabel', principalmente na dose de 400 mg L -1 aos 7 DAV + 10 DAC, além de propiciar a melhoria no atributo cor das bagas. Palavras-chave: Vitis labrusca, suco de uva, antocianina AbstractThe grape 'Isabel' main cultivar used for juice production in Brazil has a deficiency of coloring and an alternative is the application of abscisic acid (S-ABA), since the accumulation of anthocyanins, 1 Eng as Agr as , Discentes do Curso de Doutorado