Abstract
In recent years, among the various vineyard treatments adopted for table grape cultivation, there was a significant use of plant growth regulators (PGRs) and green pruning (i.e., girdling) to increase the berry size and the consequent yield. In particular, an increase in application of forchlorfenuron (CPPU) and gibberellic (GA3) acid for many seeded and seedless table grape cultivars was registered in several table grape producing countries. In this two-year study, girdling at berry-set, gibberellic acid (10 ppm) applied at berry diameter of 10–11 mm and forchlorfenuron (9.75 ppm) applied at berry diameter of 11–12 mm were investigated to verify their effects on berry size, yield, chemical and metabolic characteristics of the grapes.
In general, at harvest, all treatments (girdling, GA3 and CPPU) showed a significant increase of berry diameter, length and weight and consequent bunch weight and yield/vine compared to untreated berries. The treatments showed significant differences for the colorimetric parameters, in particular, a higher value of the hue (h°) for GA3 and CPPU treated berries, thus shifting the skin color from yellow towards a yellow-greenish one. Metabolomic study carried out by Nuclear Magnetic Resonance (NMR) spectroscopy combined with Principal Component Analysis (PCA) indicated that metabolic profile depends on the year and, in each year, the effect of treatments consisted of a slight variation of the amino acid content. Influence of the treatments was found more pronounced in theyear characterized by a cooler summer.
- ©2014 by the American Society for Enology and Viticulture
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