Abstract
Color and other quality parameters of “Redglobe” grape (Vitis vinifera L.) berries were evaluated after treatment with brassinosteroid (BR) analogs. Three BRs analogs (24-epibrassinolide, Triol, or Lactone) were applied at three concentrations (0.0, 0.4, or 0.8 mg⋅L-1), at the onset of veraison. A commercial formulation (B-2000®) was also applied, at a recommended rate of 0.06 mg⋅L-1. The tested BR analogs were effective improving berry color (evaluated as color index for red grapes, CIRG), increasing the levels of soluble solids and anthocyanins, and changing the types of anthocyanins present without altering other quality and yield parameters. The effects of BR analogs on color enhancement could be explained by an increase in soluble solids content and/or anthocyanin content. Treatment with 24-epibrassinolide (at 0.4 mg⋅L-1) or the commercial formulation tended to favor the production of dihydroxylated anthocyanins, which are responsible for the red and pink colors of grape berries. Results indicate that the use of BRs constitutes a potential tool in the production of table grapes. This is the first report of this enhancement effect in a productive context.
Highlights
The assessment of table grape quality is traditionally based on sensory attributes such as flavor, aroma, texture, and color
Exogenous application of growth regulators is an important tool for improving the quality parameters of grape berries, including size, organoleptic characteristics, and color, among others (El-Kereamy et al, 2003; Han and Lee, 2004; Jeong et al, 2004; Symons et al, 2006; Fanzone et al, 2010; González et al, 2012; Xi et al, 2013)
Most studies on BRs as growth regulators have been performed on grapes for wine-make and involve the testing of only one BR analog, 24epibrassinolide (Symons et al, 2006; Luan et al, 2013; Xi et al, 2013; Xu et al, 2015), limiting the understanding of the scope of this potential tool in a productive context in the case of table grapes
Summary
The assessment of table grape quality is traditionally based on sensory attributes such as flavor, aroma, texture, and color. Minimum quality standards can be obtained by performing good management practices in the vineyard (Cameron, 1994; Schrader et al, 1994), but in the case of grape varieties such as “Redglobe,” which has large-sized berries and clusters, these practices can lead to overproduction. Under these conditions, “Redglobe” berries fail to develop suitable red color (Kliewer and Weaver, 1971; Schrader et al, 1994; Kliewer and Dokoozlian, 2005). These techniques include the use of growth regulators such as ethephon and/or abscisic acid (ABA) during veraison; these techniques have been widely
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