HighlightGrapevine red blotch interferes with the hormonal and transcriptional regulation of berry development, leading to suppression of secondary metabolism and induction of photosynthesis at late ripening stages.

No abstract

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.

-The objective of this work was to evaluate the effect of ethephon and of abscisic acid (ABA) application timing on the color of 'Rubi' Table grape. Eight treatments were evaluated: control, without application; ethephon 500 mg L -1 applied seven days after veraison (7 DAV); and two concentrations of ABA (200 and 400 mg L -1 ) arranged with three application timings at 7 DAV, at 15 days before harvest (DBH), and at 7 DAV + 15 DBH. ABA does not modify physical-chemical characteristics of the cluster and improves the color of grapes, especially when applied twice (7 DAV + 15 DBH) at the concentration of 400 mg L -1 .Index terms: Vitis vinifera, ABA, anthocyanins, plant growth regulator. Uso do etefon e épocas de aplicação do ácido abscísico para melhorar a cor da uva de mesa 'Rubi'Resumo -O objetivo deste trabalho foi avaliar o efeito do etefon e de épocas de aplicação do ácido abscísico (ABA) na cor da uva de mesa 'Rubi'. Oito tratamentos foram avaliados: controle, sem aplicação; etefon 500 mg L -1 , aplicado sete dias após o início da maturação (7 DAIM); e duas concentrações de ABA (200 e 400 mg L -1 ) arranjadas em três épocas de aplicação, aos 7 DAIM, aos 15 dias antes da colheita (DAC) e aos 7 DAIM + 15 DAC. O ABA não altera as características físico-químicas dos cachos e melhora a cor das uvas, especialmente quando aplicado duas vezes (7 DAIM + 15 DAC), à concentração de 400 mg L -1 .

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.

a b s t r a c tThe objective of this work was to evaluate the incidence of gray mold of the new seedless table grape 'BRS Vitoria' grown under subtropical conditions, during the cold storage. Grape bunches were obtained from a commercial field trained on overhead trellis and located at Marialva, state of Parana (PR) (South Brazil). The trials were conducted on two consecutive seasons, regular and out of season crops of 2013. Grapes were subjected to the following treatments in a cold chamber: (i) cold storage at 0 • (control); (ii) cold storage at 0 • C with SO 2 pad; (iii) cold storage at 0 • and inoculated with Botrytis cinerea suspension; (iv) cold storage at 0 • C with SO 2 pad and inoculated with B. cinerea suspension. The randomized design was used as statistical model with four treatments and five replicates, with 20 bunches per plot. The incidence of gray mold on grapes was evaluated at 30 days after the beginning of cold storage and at 7 days at room temperature after the end of cold storage. Grape physicochemical variables, such as bunch mass, berry firmness, bunch mass loss, skin color, soluble solids (SS), titratable acidity (TA) and SS/TA were evaluated at the beginning and 30 days after the period of cold storage. The results of this study showed that a good reduction of gray mold was achieved by SO2 during cold storage and shelf life periods. Also, bunch mass, berry firmness, mass loss, color, SS, TA and SS/TA of the grape tested was not negatively affected by SO 2 treatment. A good control of gray mold could be achieved on 'BRS Vitoria' table grapes by sulfur dioxide during storage without affecting fruit quality.

-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.