Carmela Pacucci

Girdling, Gibberellic Acid, and Forchlorfenuron: Effects on Yield, Quality, and Metabolic Profile of Table Grape cv. Italia

Among the various vineyard treatments adopted in recent years for table-grape cultivation, there has been a significant use of plant growth regulators (PGRs) and girdling to increase berry size and yield. In particular, an increase in the application of forchlorfenuron (CPPU) and gibberellic acid (GA3) for many seeded and seedless table-grape cultivars has been registered in several countries. In this two-year study, girdling at berry set, gibberellic acid (10 mg/L) applied at berry diameter of 10 to 11 mm, and forchlorfenuron (9.75 mg/L) applied at berry diameter of 11 to 12 mm were investigated to verify their effects on berry size, yield, and chemical and metabolic characteristics of Italia grapes. In general, at harvest all treatments significantly increased berry diameter, length, and weight and consequent cluster weight and yield/vine compared to an untreated control. The treatments showed significant differences for the colorimetric parameters, in particular a higher value of hue for berries treated with GA3 and CPPU, thus shifting the skin color from yellow toward yellow-green. Metabolomic study carried out by nuclear magnetic resonance spectroscopy combined with principal component analysis indicated that metabolic profile depends on the year and, in each year, the effect of treatments consisted of a slight variation of amino acid content. Treatments effects were more pronounced in the year characterized by a cooler summer.

Ethephon As a Potential Abscission Agent for Table Grapes: Effects on Pre-Harvest Abscission, Fruit Quality, and Residue

Some plant growth regulators, including ethephon, can stimulate abscission of mature grape berries. The stimulation of grape berry abscission reduces fruit detachment force (FDF) and promotes the development of a dry stem scar, both of which could facilitate the production of high quality stemless fresh-cut table grapes. The objective of this research was to determine how two potential abscission treatments, 1445 and 2890 mg/L ethephon, affected FDF, pre-harvest abscission, fruit quality, and ethephon residue of Thompson Seedless and Crimson Seedless grapes. Both ethephon treatments strongly induced abscission of Thompson Seedless berries causing >90% pre-harvest abscission. Lower ethephon rates, a shorter post-harvest interval, or berry retention systems such as nets, would be needed to prevent excessive pre-harvest losses. The treatments also slightly affected Thompson Seedless berry skin color, with treated fruit being darker, less uniform in color, and with a more yellow hue than non-treated fruit. Ethephon residues on Thompson Seedless grapes treated with the lower concentration of ethephon were below legal limits at harvest. Ethephon treatments also promoted abscission of Crimson Seedless berries, but pre-harvest abscission was much lower (≅49%) in Crimson Seedless compared to Thompson Seedless. Treated fruits were slightly darker than non-treated fruits, but ethephon did not affect SSC, acidity, or firmness of Crimson Seedless, and ethephon residues were below legal limits.

The table grape ‘Victoria’ with a long shaped berry: a potential mutation with attractive characteristics for consumers

BACKGROUND Puglia is the most important region in Italy for table grape production. Since consumers look for new products, the number of table grape varieties has greatly increased in recent years. RESULTS In a survey in the Puglia region, we identified several years ago a potential mutation of the cv. Victoria. We described this accession in comparison with the standard Victoria for some amphelographic traits. All the characteristics were very similar to the standard Victoria except for the berry shape, which was significantly more elongated. Moreover, the berry of the mutated Victoria showed higher firmness, lightness and chroma than the standard one, with a more intense yellow colour of the skin (appreciated by consumers). The molecular characterisation with 25 SSR markers showed that normal and mutant Victoria were genetically identical at all the analysed loci, thus suggesting that the two accessions could be considered as clones with the difference in berry shape probably due to a somatic mutation. CONCLUSIONS This mutation of the cv. Victoria may have interesting perspective for the market since consumers are always attracted by different shape and colour of the fruits (consumers buy with eyes). This accession can be an alternative clone of the already known standard Victoria.