Effect of Gibberellic acid (GA3) inflorescence application on content of bioactive compounds and antioxidant potential of grape (Vitis L.) 'Einset Seedless

South African Journal of Enology and Viticulture, Feb 2019

Gibberellic acid (GA3) is a plant growth regulator widely used in the cultivation of seedless grape varieties to increase their yield. Hormonisation treatment has beneficial effects on yield size and quality, yet its influence on the level of biologically active compounds and grape antioxidant activity has not yet been studied extensively yet. Clusters of 11-year-old 'Einset Seedless' grapevines trained according to the single Guyot pruning style were sprayed with GA3 at 100, 200 or 300 mg/L dose once, twice or three times. Fruit harvested on 25 September were immediately examined for acidity, extract content, biologically active substances and antioxidant capacity using the DPPH test. In addition, correlations occurring between some parameters measured were calculated. Hormonisation had a negative effect on the content of extract, flavonoids and ascorbic acid, while it had no effect on the anthocyanin level. The antioxidant activity determined by the DPPH assay depended on dose and the number of treatments, and the analysed parameters were shown to decrease significantly with increasing application number. Gibberellic acid at 100 and 300 mg/L application rates had a significantly increased DPPH level compared to the control and 200 mg/L dose. The single GA3 treatment, and when applied three times, and application rates at 100 and 200 mg/L were shown to have a significant influence on phenolic acid content. The level of tannins after a single GA3 treatment and a 300 mg/L dose increased significantly.

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Effect of Gibberellic acid (GA3) inflorescence application on content of bioactive compounds and antioxidant potential of grape (Vitis L.) 'Einset Seedless

ORIGINAL RESEARCH   Effect of Gibberellic acid (GA3) inflorescence application on content of bioactive compounds and antioxidant potential of grape (Vitis L.) 'Einset Seedless' berries     M. KaplanI, * ; A. NajdaII; K. KlimekIII; A. BorowyI IDepartment of Pomology and Nurseries, University of Life Sciences, 58 Leszczynski Street, 20-068 Lublin, Poland IIDepartment of Vegetable Crops and Medicinal Plants, University of Life Sciences, 58 Leszczynski Street, 20-068 Lublin, Poland IIIDepartment of Applied Mathematics and Informatics, University of Life Sciences, 28 Gleboka Street, 20-612 Lublin, Poland     ABSTRACT Gibberellic acid (GA3) is a plant growth regulator widely used in the cultivation of seedless grape varieties to increase their yield. Hormonisation treatment has beneficial effects on yield size and quality, yet its influence on the level of biologically active compounds and grape antioxidant activity has not yet been studied extensively yet. Clusters of 11-year-old 'Einset Seedless' grapevines trained according to the single Guyot pruning style were sprayed with GA3 at 100, 200 or 300 mg/L dose once, twice or three times. Fruit harvested on 25 September were immediately examined for acidity, extract content, biologically active substances and antioxidant capacity using the DPPH test. In addition, correlations occurring between some parameters measured were calculated. Hormonisation had a negative effect on the content of extract, flavonoids and ascorbic acid, while it had no effect on the anthocyanin level. The antioxidant activity determined by the DPPH assay depended on dose and the number of treatments, and the analysed parameters were shown to decrease significantly with increasing application number. Gibberellic acid at 100 and 300 mg/L application rates had a significantly increased DPPH level compared to the control and 200 mg/L dose. The single GA3 treatment, and when applied three times, and application rates at 100 and 200 mg/L were shown to have a significant influence on phenolic acid content. The level of tannins after a single GA3 treatment and a 300 mg/L dose increased significantly. Keywords: Seedless grape, hormonisation, DPPH, anthocyanins, correlation     INTRODUCTION Grape consumption is strongly correlated with the reduced risk factor for developing chronic diseases, such as cardiovascular disorders and cancer (Arts & Hollman, 2005; Erdman et al., 2007; Leifert & Abeywardena, 2008; Vislocky & Fernandez, 2010; Doshi et al., 2015). This results from, among others, the presence of biologically active compounds like polyphenols, which display powerful antioxidant effects, along with anti-inflammatory, anti-carcinogenic and anti-platelet properties. Polyphenols also help dilate blood vessels, boost the immune system and play a neuroprotective role, attributed mainly to their ability to modulate and induce signalling pathways (Frankel, 1999; Stevenson & Hurst, 2007; Pezzuto, 2008; Dohadwala & Vita, 2009; Crozier et al., 2010; Vislocky & Fernandez, 2010; Xia et al., 2010; Doshi et al., 2015). Polyphenols inactivate free radicals, chelate divalent metal ions, and thus lower their oxidant potential (Scalbert et al., 2005). The qualitative and quantitative composition, distribution and antioxidant activity of polyphenols in grapes are quite variable and depend on species, cultivar, location in berry (skin, pulp, seeds, juice), climate-soil conditions (exposure to light, temperature, soil type), agrotechnical practices (irrigation, nutrient availability, application of plant growth regulators, harvest time, berry maturity, yield and berry size) and, finally, post-harvest conditions and storage-processing techniques (Kim et al., 2003; Peña-Neira et al., 2004; Jiang et al., 2006; Montealegre et al., 2006; Orak, 2007; Xia et al., 2010; Liang et al., 2011). Polyphenols are responsible for the major sensory attributes of products and beverages of plant origin, as they are the determinants of their appearance (colour) and taste, i.e. flavour, bitterness and astringency (Tomás-Barberán & Espin, 2001; Es-Safi et al., 2007). Seedless grape varieties have been on the rise in the world grape market because of their high quality and consumer preferences, and they enjoy increasing popularity not only as table grapes, but as raisins as well (Artés-Hernández et al., 2006). One of the most promising commercial seedless cultivars that can be grown successively in cool-climate areas, such as Poland, is 'Einset Seedless', a pink grape with a unique strawberry-like flavour. This variety can be used for raisin production or for fresh consumption as table grapes. However, the natural berry size of the 'Einset Seedless' variety (± 2 g) is not large enough for table grape use and thus represents a problem for commercialisation. To overcome this problem, and to improve grape size and quality, plant growth regulators (most often gibberellic acid, GA3) are applied global (...truncated)


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M. Kaplan, A. Najda, K. Klimek, A. Borowy. Effect of Gibberellic acid (GA3) inflorescence application on content of bioactive compounds and antioxidant potential of grape (Vitis L.) 'Einset Seedless, South African Journal of Enology and Viticulture, pp. 1-10, Volume 40, Issue 1, DOI: 10.21548/40-1-3004