The Effect of Ethephon on the Berry Colour of Flame Seedless and Bonheur Table Grapes
Abstract
Flame Seedless grafted onto Richter 99 situated in the Lower Orange River region and Bonheur grafted onto Ramsey in the Berg River Valley region of South Africa were used to test ethephon treatments for berry colour improvement. The trial was repeated over three seasons. Four ethephon dosages (100, 200, 300 and 400 mg/L) in combination with five application times (weekly intervals starting from acid maximum) were compared to anuntreated control. As soon as general minimum maturity for export was reached, pack-out percentage was determined and representative bunch samples harvested and packed as for export. After storage for four weeks at -0.5°C and one week at l0°C, bunch quality was evaluated according to standard industry norms. As a preliminary determination anthocyanin and phenol absorbance levels were determined during one season to possibly complement visual evaluation of berry colour. The best overall result with regard to the timing of application for both Flame Seedless and Bonheur was obtained with an ethephon application two weeks after acid maximum (30 to 40% colour). Significant seasonal differences were observed regarding various quality variables of Bonheur. This timing was not very critical for improved export pack-out or meeting the berry colour quality norm. Treatments closer to harvest increase the risk of quality defects during cold storage, such as berry crack, S02 burn, as well as soft and loose berries. An ethephon dosage of 300 mg/L for Flame Seedless and 200 mg/L for Bonheur gave satisfactory results regarding export pack-out, export-quality berry colour at harvest and post-cold-storage quality. The preliminary evaluation of anthocyanin and total phenol absorbance levels did not correlate well with visual evaluation of berry colour, showing the difficulty of sensory determinations for quality evaluation.
Downloads
Copyright (c) 2017 South African Society for Enology and Viticulture

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
A copyright form will be e-mailed to the corresponding author when the manuscript has been accepted for publication.
In principle, the Author agrees to the following when he/she signes the copyright agreement:
I hereby assign to the SOUTH AFRICAN SOCIETY FOR ENOLOGY AND VITICULTURE (SASEV) the copyright of the text, tables, figures, supplementary material, illustrations and other information (the Material) submitted with the manuscript to be published in SOUTH AFRICAN JOURNAL OF ENOLOGY AND VITICULTURE (SAJEV) (the "Article"). The copyright becomes effective from the date the Article has been accepted for publication in SAJEV.
This is an open access journal, and the authors and journal should be properly acknowledged, when works are cited.
Author's may use the publishers version for teaching purposes, in books, theses, dissertations, conferences and conference papers.
A copy of the authors' publishers version may also be hosted on the following websites:
- Non-commercial personal webpage or blog.
- Institutional webpage.
- Authors Institutional Repository.
The following notice should accompany such a posting on the website: This is an electronic version of an article published in SAJEV, Volume XXX, number XXX, pages XXX - XXX, DOI. Authors should also supply a hyperlink to the original paper or indicate where the original paper (www.journals.ac.za/index.php/sajev/) may be found.
Authors publishers version, affiliated with the Stellenbosch University will be automatically deposited in the University's Institutional Repository SUNScholar.
Articles as a whole, may not be re-published with another journal.
The following license applies:
Attribution CC BY-NC-ND 4.0